Glossary of General Terms


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1. A person who has the technological access on a computer workstation, server, or network system to make configuration changes, such as installing new software, specifying program settings and parameters, setting up or deleting user accounts and mailboxes, resetting passwords, and/or changing access permissions for other users. Non-administrators are blocked from making these kinds of changes, and from seeing any information about a computer or network system (such as security logs) that an ordinary user should not be able to see, in order to preserve the integrity of the system as well as confidentiality of data.

2. A person whose job is to perform configuration tasks, diagnose problems, and collect performance information on IT and communications systems.


Software that constantly runs on your computer, monitors your activities, and makes ads appear that it thinks are relevant to what you are looking at on the Internet. Adware is considered malicious and illicit, and most security software packages will attempt to remove it from your computer.

See also: malware, spyware


A software component running on a computer or device that communicates with a centralized management system to provide enhanced functionality. Agents can gather inventory information, gather logs, scan for viruses, scan for needed updates, perform file backups, and create a snapshot of a database, to report back to the management system. This can enable more secure, detailed, thorough, and accurate information and function than if the management system tries to perform these tasks through network requests to standard operating system interfaces (called agentless management). Agentless management does have the advantage that agent software does not need to be installed on remote managed systems.


As opposed to "digital", this term refers to a method of storing or transmitting sound or television images by physically duplicating the electromagnetic waves onto some kind of recording medium (like a magnetic tape or vinyl disc) or through airwaves or electric wire. Compared to digital, the quality of an analog recording or transmission is intrinsically superior, but subject to degradation and interference. Computer equipment cannot store data in analog format.

See also: digital


See: anti-virus


Software that examines files on a computer's hard drive, attachments in e-mails received, and files downloaded from websites, to determine if the file is a virus, and automatically delete or quarantine any viruses found. Anti-virus software usually looks for similar types of malicious software, such as adware or spyware. It works by recognizing known virus files by their exact contents, or by observing that an unrecognized program file behaves like a virus (this is called heuristics). Anti-virus software can run on a workstation or server as described above, or on a network device that can inspect files as they traverse the device.

See also: adware, spyware, malware, intrusion prevention system (IPS), anti-spam, unified threat manager (UTM)


Software that attempts to block unsolicited commercial e-mail (junk mail, or spam) from arriving in users' mailboxes. This can work by one or more of the following methods:

a. Examining the content of each message for known phrases, links to known illegitimate websites, or many other indicators that a message is an advertisement;

b. Blocking known senders of spam from sending any messages at all, regardless of content, based on block lists that are constantly updated through block list aggregators;

c. Using custom blacklists and whitelists to disallow and allow, respectively, messages from a given sender.

Anti-spam software can run on a workstation, e-mail server, or on a network device that can inspect messages as they are transferred from the e-mail server to the workstation. Although spam is often associated with viruses due to the fact that some viruses are transmitted via e-mail, anti-spam and anti-virus software perform distinct functions: anti-spam focuses on inbound e-mail, while anti-virus protects agains malicious program files regardless of their source. Also, although the term "spam" can apply to unwanted messages in media other than e-mail (such as comments on a web site), anti-spam software generally focuses only on e-mail spam, as this is by far the most disruptive and annoying of anything that can be called "spam".

See also: anti-virus, unified threat manager (UTM), spam


A package of software designed for you to accomplish tasks on a computer workstation. Examples for a typical computer include Microsoft Word (word processing), Microsoft Outlook (e-mail and calendar), Intuit QuickBooks (accounting), Mozilla Firefox (web browsing), Google Earth (planet browsing), a calculator, Adobe Dreamweaver (developing websites), a DVD player, a video editor, a chess game, a backup system, etc. The term fell out of common use for a while until late last decade, as mobile phones became capable of supporting installable applications. In the mobile phone realm, applications are called simply "apps". Server-based network applications run on a network-connected server (either in-house or on the Internet), to centrally store data and enable real-time collaboration.


See: system architecture


Acronym for American Standard Code for Information Interchange. It is a translation table, developed in the 1960s, that assigns a one-byte numeric value to letters, numerals, and punctuation marks. Since computers store all data as a series of numbers, different applications can handle each other's text files only if they use the same translation table. ASCII is the most common standard for simple text files on personal computers. Sometimes people use the term "ASCII text" to mean "plain text".

See also: plain text


An ordinary computer file sent from one user to another through e-mail. Typically this is a word processing document, spreadsheet, photo, video file, or even an executable file.


The process of recording information about events by a computer or network device, for the purpose of later analysis to assess performance, or for forensics in the case of unauthorized access.

See also: log file


The process of confirming, through technological or other measures, that a user is who he says he is when trying to access protected information or services on a network. This can be done by typing a password or inserting a key card. For communications and network security, it also refers to ensuring that the source and/or target of a transmission is the intended source/target and not an impostor.

See also: password, certificate, smart card


Permissions granted for a user, or a software process, to access data; this permission also specifies whether the data may be read only and/or modified. Authorization is configured at the technological level, but specified by business managers with proper authority, defined either based on the identity of the user and the content of the data, or based on other less well-known schemes, such as formal abstract security models not discussed here.


An information security term that refers to necessary services and applications being up and running, and with data present and online, so users are able to log in and do their work. It also applies to communications systems' being operational.

See also: confidentiality, integrity


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The symbol \ which is usually above the Enter (or Return) key on your keyboard. Not to be confused with the regular slash / that is usually on the same key as the question mark, near the right Shift key. When typing a command or network address, you must use the correct type of slash depending on the application and the computer platform.


1. Formally, one or more copies of data or configuration information made for the purpose of recovery in case hardware failure or human error deletes or corrupts the data, or for archiving previous versions for historical purposes.

2. Colloquially, a secondary piece of equipment ready to be employed in case the primary device fails.

See also: replication

battery backup

See: UPS


See: business intelligence


This term can have two meanings, depending on context:

1. Information stored on your computer in a format usable by your computer, such as configuration data or executable program code, as opposed to the human-readable text or program source code.

2. A series of bits, with values of either 0 or 1, analogous to the state of electrical charges inside the computer chip, which is the underlying format in which computers store all information.

See also: bit


Acronym for Basic Input/Output System. This is software stored in chips inside your computer. This software is the first to run when you turn on your computer. It is responsible for executing the computer's initial self-tests and loading your operating system from your hard drive. Sometimes a technician needs to edit its settings, using a special method that varies among computer models, to control how your computer starts up or how internal components interact with each other.

See also: firmware, motherboard


The smallest unit of data storage on a computer, represented by a 0 or 1.

See also: binary, byte


A type of computer file that stores an uncompressed photo or other graphical image.

See also: GIF, JPEG, PNG


Short for web log; a website usually maintained by an individual author in diary form, with updates shown in reverse chronological order, covering anything from specific topics to just general observations and random essay topics. These were very popular in the early- to mid-2000s, until supplanted by the next generation of vapid social media sites such as MySpace, Facebook, and Twitter. Many active blogs, with long, thoughtful articles, are still online.

See also: website, WordPress, MySpace, Facebook, Twitter


This is a very low-power, close-range wireless system for connecting small devices, such an earpiece/microphone to a mobile phone. It was developed in the late 1990s. In the early days, there were implementations for connecting a mobile phone to a personal computer to synchronize data, for connecting to printers wirelessly, and for wireless keyboards and mice, but these have all been superseded by different wireless technologies (although Apple still uses it for its keyboards and mice). The term itself is actually a trademark owned by the Bluetooth Special Interest Group and licensed to manufacturers of Bluetooth equipment, so in practice the term is used to refer to the system itself rather than any particular product.


A message you get in your e-mail box telling you that an e-mail you sent could not be delivered, usually including technical information about the nature of the problem.


An IT equipment installation or upgrade project that is integrated with existing equipment or infrastructure already exists, or which must interoperate and maintain compatibility with existing equipment, protocols, standards, processes, data, and applications. This term also applies to a software development project that must integrate with existing software.

See also: greenfield


In reference to computer files, this means manually navigating through a file folder hierarchy using your mouse or keyboard, looking at the names of folders to presume their content, and looking at lists of filenames to find what you need. Similary, in reference to the web, this refers to clicking on links to go from one page to the next.

See also: search


See: web browser


A temporary holding area of a computer's internal memory (RAM) for data being sent or received. When information comes in to the buffer, the computer processes it and moves it to where it needs to go, then clears the buffer so that more information can be received.

See also: buffer overflow

buffer overflow

A problem that occurs when a computer sends more data than a receiving computer can fit in its buffer. If the receiving computer is running poorly designed software, it may mistakenly place the excess data into areas of its memory outside the buffer, replacing other data or program code in use. This can cause the computer to crash, or even allow a clever criminal to deliberately replace legitimate program code with a virus.

See also: patch


A fault in any computer operation attributed to a mistake made by the programmer when the software was first developed, as opposed to a transient operational problem. To fix a bug, you need to either employ a workaround (that is, complete your work using some method that avoids the bug), or apply a patch from the software publisher that fixes the bug (if available).

See also: crash, error


A package of software that has been compiled after reaching a certain milestone for features or bug fixes, and having been checked for consistency amongst different components. Build numbers distinguish one from the other. Build numbers are a subset of version numbers. A version number defines the broad feature set and identity of a software product and is included in the packaging and advertising, whereas only system administrators are concerned with the different builds within a version.

See also: compile, software, bug

business intelligence

Advanced analysis of data, performed by specialized software tools, that answers questions to support business decisions. An example might be making graphs of when customers purchase tickets for a type of concert, in order to plan timing of advertising.


A unit for measuring quantities of data. One byte is comprised of eight bits, and can store 256 different values. These values can have whatever meaning is assigned by the application using that byte (such as a raw number from 0-255, a program instruction, or an ASCII-encoded letter, numeral, or punctuation mark in a text file).

See also: kilobyte, megabyte, gigabyte, terabyte


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C drive

The primary hard drive of a personal computer running Microsoft Windows.

See also: hard drive

cable internet

A method of connecting to the Internet through a cable television company's coaxial wiring network.

See also: DSL, T1


Pronounced like "cash". This is a copy of a portion of data or program code, stored close to where it will be used, for the purpose of improving performance. By its nature cache storage is limited, so computers use sophisticated methods to ensure only the most relevant data is kept in cache. Also, systems must deal with the fact that data in a cache will become incorrect once the data on the original source is updated. Caching appears in every level of computing:

a. Very expensive, high-speed memory integrated into a microprocessor (called the L1 cache) to hold chunks of program code or data it's working with to improve performance over having to work with it directly in the slower system RAM;

b. System RAM holding blocks of data retrieved from the hard drive (called disk cache), so that a program working with it doesn't have to repeatedly access the hard drive (which operates thousands of times slower than system RAM)

c. Domain name lookups being saved by your computer (called the DNS cache) to save time looking up the IP address repeatedly over the network if you access the same website or mail server repeatedly;

d. A caching proxy server at the edge of a company network that stores the contents of entire web pages so that dozens or hundreds of users can view the same page after the server has downloaded it only once through the company's Internet connection.

See also: proxy server

case sensitive

When a computer compares strings of text to one another in a case-sensitive fashion, an uppercase letter is seen as different from a lowercase letter, so the strings "Mongo" and "mongo" will not match. This is typically an issue when you are typing a password. In contrast, e-mail addresses are not case sensitive. Case sensitivity might also apply when dealing with file names. In UNIX-based operating systems, file names are case sensitive, so you can have two distinct files in the same directory, one named "readme.txt" and the other "ReadMe.txt". In Microsoft Windows operating systems, file names are not case sensitive, so if you already have a file named "readme.txt" in a folder and you try to save a new file named "ReadMe.txt", the system will overwrite the first file with the new file.


See: compact disc


The type of wireless communications network used by common mobile phones, comprised of communications towers positioned every few miles throughout the coverage area. The coverage area of each tower is called a "cell", and each cell should overlap to an extent with each adjacent cell to provide reliable service while users move about.

See also: satellite


See: digital certificate


A single letter, digit, punctuation mark, or space.

See also: string

character set

A set of letters, numerals, symbols, and punctuation marks used in a given language and/or regional context, and which defines what character a given ASCII code or Unicode value represents.

See also: ASCII, Unicode


See: instant messaging (IM)


See: hyperconvergence


A computer or piece of software that requests information and services from another computer (the server). Examples include an e-mail client such as Microsoft Outlook or Mozilla Thunderbird, a web client (also called a browser) such as Microsoft Internet Explorer or Mozilla Firefox, and an FTP client for accessing files on an FTP server.

See also: server


1. Technically, a set of servers configured to provide the services (such as websites, e-mail and other messaging systems, databases, file storage, virus scanning, voice-over-IP telephony, and other applications) on demand over the Internet to vast numbers of users. Resources provided by the equipment comprising the cloud system (processing power, storage, and network bandwidth) are managed as a pool, so the system can be elastic, meaning it can reallocate resources to meet spikes in service requests. This is opposed to conventional hosted services which might run on a one or a few servers, with a fixed number of customers, and a given customer's data tied to a given server. The term is derived from the use of a cloud-like icon by IT systems engineers for many years to represent an abstract network in system diagrams. Previously, this was called "utility computing". Cloud computing has become more prevalent in recent years due to investments in infrastructure by huge companies like Google, Amazon, Rackspace, and Microsoft, as well as the maturity of virtualized computing, which is a key factor in enabling elasticity.

2. Colloquially, "the cloud" is a buzzword that has replaced what was formerly called simply "hosted services", referring often to any service provided over the Internet. For example, some conventional website hosts and Internet-based e-mail security security providers have in recent years added the "cloud" moniker to their marketing material, even as customer accounts are still tied to particular servers. Also, some vendors of hardware that can be configured to enable remote access refer to this access as "cloud-based" instead of properly calling it "Internet-based". For example, the maker of a storage device you can install in your facility, and then access via the Internet, might inaccurately say you've enabled "cloud" access to your data.

See also: virtual, hosted service, private cloud, public cloud, hybrid cloud


The part of a computer program comprised of instructions and logic, which drives everything a computer does.


See: colocation


A server, such as a web server, database/application server, or e-mail server, owned by the company that uses it, but stored in a hosting provider's facility. This is done to improve performance and uptime, as a decent hosting provider will have redundant connections to the Internet and backup electrical generators, and to improve security, as the server can be in a locked cage with an alarm inside the hosting provider's secure facility, and monitored 24 hours a day, as opposed to sitting in a closet in the company's office suite.

See also: hosted service

combo box

A selection list that also allows you to manually type in an item that is not in the list.

See also: list box

command-line interface

A system wherein you operate your computer by typing commands line-by-line; after each command, the computer will generally provide feedback on the result of your command in the next line of text. There are no icons, menus, or checkboxes with options to set for your programs. A command-line interface was used in early computers that did not have the technological capability to present a graphical user interface (GUI). It is also useful today in situations that require the power and versatility of the virtually limitless functions that can be carried out at a command line.

See also: GUI

compact disc

A 4.5-inch plastic disk using optical technology designed in the 1980s for digital music playback, and adapted for computer use as a data storage medium. A compact disc (CD) can store from 650 to 700 megabytes. Most commonly used for distribution of software, with the data stamped onto the disk at the factory. The technology was further adapted in the 1990s to support on-the-fly recording using an ordinary computer outfitted with a CD recorder, and special recordable CDs (called either CD-R or CD-RW). CD-R discs are are less expensive, but any data recorded on them cannot be overwritten or erased. CD-RW discs are more expensive, but offer the flexibility of overwriting or erasing data.


The process of turning software source code into binary program files that can be directly executed by a computer or mobile device. Software must be compiled for the particular microprocessor and operating system on which it will run.

See also: source code, program, software


A method of mathematically manipulating data to store the same information in less physical space on a tape or hard drive, or to transfer it over the Internet in less time. For most types of compressed files and communications, methods are used that will allow the data to be uncompressed to exactly what it was before compression. Photographs, movies, and audio files achieve a higher level of compression by permanently reducing the quality, usually imperceptibly.

See also: JPEG, MP3, zip file


The box that contains the hardware to run programs and store data, as well as ports and slots for connecting peripherals and communicating with other computers. Today, although this box forms the central part of a versatile business, communications, and entertainment system, we still call it a "computer" because of its origin as a device that merely performed mathematical computations.

See also: monitor, desktop, laptop, tower


An information security term referring to protecting information from unauthorized disclosure. Disclosure can mean:

1. Information being available to users or the public by accessing systems that are misconfigured and provide the information without required login.

2. Information being transmitted on untrusted networks without encryption or with weak encryption, enabling unauthorized users to observe the information in transit.

3. User account permissions being technically misconfigured, or configured properly but not in alignment with operational policy, allowing a user to access files that the user should not be able to access.

See also: availability, integrity


In general, the manner of implementing information technology systems at the operational level. Particularly, this includes the number of devices, how they are connected, peripherals and options attached to each device, partitioning of storage, selection of network communications protocols, software available, software programs and versions installed, software components running or scheduled to start, location and segmentation of databases, commands issued, and the value of numeric settings and other data to set software options for computers and other devices.

See also: system architecture

configuration management

The process of documenting configuration in a methodical manner to enable holistic analysis, assess the effect of proposed changes, and record a log of changes. Proper configuration management assists with preventing problems, determining the cause of problems, and rolling back problematic changes.


1. The process by which separate nodes in a network synchronize their respective copies of a shared database, set of rules, or algorithm, which are used to work cooperatively. A few examples are OSPF (routing protocol) and Microsoft Network Load Balancing (NLB).

2. A design or engineering process of combining disparate functions or technologies into the same system, which can improve capabilities and manageability. The term has applied over the years to various disciplines and technologies. Examples: moving telephone service from a PBX with separate wiring onto your computer network using VOIP technology which enables synchronizing directories and managing voicemail from a desktop computer; combining user-owned cellular devices into your company's wireless infrastructure; moving physical routers and firewalls into your virtual machine infrastructure with network virtualization; and moving network storage devices onto the compute resources of a datacenter by having virtual machine hypervisors combine their local storage into a virtual SAN.

See also: hyperconvergence


A text file that a web site puts on your computer to record information about what you did on the site. When you visit the web site again, the site can then pull that file from your computer to figure out who you are, and display things as they were before. Cookies are sometimes derided as a security threat, because web sites can read cookies left on your computer by other web sites, although cookies were originally designed not to allow this. The consequences are, theoretically, that a malicious web site can gain a saved password or other personal information you used on a legitimate site, which you did not intend for the malicious web site to have.


A state in which data is physically present, but the data has been changed in a manner that is not intended. This can occur due to software error, hardware malfunction, error or malicious acts by users, or an improper computer shutdown rendering updates to the data only partially complete. Examples include:

1. A document file that cannot be opened in its associated program (such as a word processor), preventing a user from viewing, printing, or editing the contents of the file.

2. A database with internal indexes that are not consistent, due to a sudden power loss on a server with no battery backup, preventing the server from making the database available.

3. A database table where all data in a particular column was accidentally set to the same value by a database administrator's mistake. If this were a User ID field, for example, then all information related to users elsewhere in the database (such as dates/times logged on and off, permissions assigned, files owned, and what's saved in each user's profile) would be disassociated from each user, rendering the application that depends on this database unusable.

4. A configuration file inside a router that turned into scrambled nonsense due to a fault in the internal storage, rendering the router unable to perform its functions.


Central Processing Unit. Formally, this refers to the microprocessor inside your computer, but sometimes people use it to refer to the computer itself.

See also: computer, microprocessor


A broad term describing the total failure of a program, computer component, or the computer itself, as opposed to a simple quirk or error message. For example, a program is said to crash when it stops responding to mouse clicks or keypresses, and you cannot recover the data you were working on. A computer is said to crash if it shuts down suddenly or fails to power on, or if everything on the screen freezes to the point you have to unplug it to try to start it again. A hard drive is said to crash when it physically fails to operate, rendering all the programs and data on it inaccessible, often permanently.

See also: bug, error


Acronym for customer relationship management system. It is software that maintains product information and tracks customer contacts, past purchases, aggregate trends, and demographics to enable automated quoting systems, lead generation, sales call reminders, etc. This is usually a major application that is implemented as a special project along with significant investment in training; it's not generally something you can just buy and install from a disk, like typical desktop software. Leading providers of CRM software are Salesforce, SAP, and Oracle.

See also: ERP, HRMS


Acronym for cathode ray tube, the technology used in computer monitors and television sets for many decades, before being replaced by LCD (flat screen) in recent years.

See also: LCD


A marker on the screen to indicate where action will take place. On a screen of text, this will indicate where anything typed on the keyboard will be inserted into the existing text. A mouse cursor indicates where action will be applied when a button is clicked or double-clicked.


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An older term from the UNIX world referring to what we now call a service.

See also: service, UNIX


A general term to refer to information managed in an organized system. A database is usually comprised of tables with rows and columns of information (text, numbers, or even images) and numerous indexes for cross-referencing. It will usually allow multiple users to access and manipulate the data at the same time, and can grow to be very large compared to typical document files. Depending on its size and type, a database may be contained in a single file, in several files in separate folders, or across several servers. The files making up the database are usually not stored alongside ordinary documents, because, unlike document files, database files must only be managed by trained personnel. Manually editing, renaming, or deleting one of the files that comprise a database can corrupt the entire database.

See also: SQL, database system

database system

Refers to the entire package surrounding a database. The basic components are:

a. The database itself;

b. User interface software that runs on personal computers or handheld devices to allow you to enter and view the data;

c. Back-end software that retrieves data and processes changes; and

d. A reporting system that enables searching, sorting, filtering, and organizing data into well-formatted printable reports for operators, executives, and clients.

Examples range from simple desktop applications (Outlook, QuickBooks) to major systems (SAP, Oracle), and many countless custom applications for job estimating, machine control, marketing, shipment tracking, inventory, club membership management, etc.

See also: database


A method by which a backup storage system saves backup storage space. During a backup, the deduplication system identifies files being backed up that already exist on the backup storage disk or tape from previous backups, and skips making another copy. Systems that do not support deduplication are not aware of the existing back up data on the backup storage device, and merely copy the same files again and again each time you run add new backups.

See also: backup


The setting for a configuration option in a computer program as specified by the programmer or system administrator; that is, the setting for any option that you have not changed in the application's configuration windows or menus. Network devices (such as switches, routers, and wireless access points) have well-known default passwords for logging in to perform remote configuration, which is referenced frequently when discussing the security implications of not changing them.


1. A single computer operated by an ordinary user, which sits on top of a table or under a desk. As opposed to a portable computer (laptop or tablet), this term refers to any full-size computer that typically does not have a monitor, keyboard, and mouse built in, and does not have a built-in battery. In this sense, the term would include what we might call a "tower" computer.

2. A computer that lays horizontally on your desk, as opposed to a tower. Often further specified as the "desktop form-factor". With such a form factor, you can place your monitor on top of the computer.

3. The main screen of any computer that you see when you are logged in but all your programs are closed or minimized, where you can click on icons to launch programs, or save files for quick and easy retrieval.

4. A general reference to the type of software that runs on an individual computer for a single user, as opposed to larger applications that run on a server with networked clients.

See also: tower


Someone who writes any kind of software, from device drivers to mobile apps to desktop or web-based applications. In the past, they have been called software engineers or just programmers.

device driver

Software which must be installed on your computer to use the devices you attach to your computer. These days, most commonly, you will only deal with device drivers for printers and scanners. Your computer already has the drivers for common devices, and will activate them as needed. If not, your computer will ask you to insert a CD that contains the drivers, or you can go to the website of the device manufacturer to download them to your computer.


Acronym for Dynamic Host Configuration Protocol. This is a system by which user workstations and other network devices can request and be assigned an IP address, and receive many other network configuration parameters, from centrally controlled server. Users don't generally need to deal with DHCP directly, as any workstation or mobile device is configured by default to use DHCP to start communicating on the network

See also: IP address


A networking term from the era of modems. It involves using an analog modem to call another computer over an ordinary telephone line, which answers the call using its own modem.


1. As opposed to "analog", this term refers to a method of storing or transmitting sound or television images in the form of numbers (digits) that can thereby be stored or transmitted by computers. This requires more expensive media (computer chips and hard drives) than analog systems. Also, compared to analog, digital recording/transmission has less fidelity to the original audio/video. But, a major advantage, which has led to the adoption of digital technology for audio and video in virtually all applications (especially as prices have come down), is the fact that, once audio or video is converted to digits, it can be duplicated and transmitted infinitely without any further loss in quality.

2. A general term relating to storage of any kind of information by a computer.

See also: analog

digital certificate

A data file derived from a network of shared and secret information, and using sophisticated methods and technologies to authenticate users or computers, encrypt data, verify the source of a message, and/or verify the identity of a website you are visiting. Often simply referred to as a "certificate".

See also: PKI

digital signature

This does NOT mean a computerized image of your hand-written signature. It refers to a method by which an e-mail message is computationally manipulated, using digital certificates, so that the recipient's computer can verify that the message was in fact sent by the sender. It is also widely used to verify that a downloaded program file came from the original publisher, and not from an impostor (who might have inserted a virus).

See also: e-signature

digital video disc

The successor to the compact disc, the digital video disc (DVD) is a 4.5-inch plastic disk using optical technology designed in the 1990s for digital video playback, and for computer use as a data storage medium. A standard DVD stores 4.7 gigabytes. Most commonly used for distribution of software and movies, with the data stamped onto the disk at the factory. The technology also supports on-the-fly recording using an ordinary computer outfitted with a DVD recorder, and special recordable DVDs (called either DVD-R or DVD-RW). DVD-R discs are less expensive, but any data recorded on them cannot be overwritten or erased. DVD-RW discs are more expensive, but offer the flexibility of overwriting or erasing data.


UNIX/Linux term for a folder.

See also: folder


An equipment failure, software malfunction, result of an errant or malicious user action, or other event (such as flood or fire) that causes information technology failures and/or data loss that, without active intervention to restore service, would impact critical business functions beyond a maximum specified threshold (how long the outage will last, the number of customers impacted, etc.). Thresholds are defined by management in relation to business requirements.

See also: high availability, fault tolerance

disaster recovery

A business process that involves restoring information technology systems to normal operations and recovering lost data in the event of an outage that, without active intervention to restore service, would impact critical business functions beyond a maximum threshold (how long the outage will last, the number of customers impacted, etc.) as specified by management. The outage can be hardware, software, or communications failure, or a loss of data due to accidental or malicious corruption or deletion.


Any kind of storage medium in the shape of a disk, from the old floppy disks to the compact discs (CDs) and digital video discs (DVDs) we use today, as well as the disks you never see that are stored inside your hard drive.

See also: drive, hard drive


Acronym for demilitarized zone. This is a network security term that has always been vaguely defined in the IT industry. It can have different meanings depending on the context, and even those have changed over the years as approaches to network security have evolved. Most commonly, this refers to an area on a business network where you put computers intended to be accessible from the Internet (such as for remote access to the corporate e-mail system, or a public web server). This area is physically separated from the heavily-protected inner portion of the network (containing user workstations and servers holding private company data), for better security. Like any component of IT system security, a DMZ is one of many options available for securing a network, and is not necessarily more secure than having your web server and workstations all in the same area. However, many business and data management policies, such as SAS 70 and PCI compliance standards, may require a DMZ to be part of the network topology. A DMZ is also known as a "perimeter network" or "screened subnet".


Acronym for Domain Name System. This is a service your computer uses to look up the IP address of a computer by its name, and vice-versa. On the Internet, it helps you find web servers and mail servers by a meaningful name (called a "domain name", such as as opposed to the IP address ( Most office networks also run an internal DNS for the company's own servers and workstations.

See also: domain name, IP address


A type of file that contains any kind of computer information you created using ordinary desktop applications, such as a letter, narrative report, chart, slideshow presentation, or spreadsheet. As opposed to the files that might make up a database, every document is an independent file, which you can edit, rename, or delete without affecting the other documents. Your operating system should associate each document with a particular program designed for you to open, view, and change the contents of the document, so that when you double-click the document icon, the appropriate program will run.

See also: file, database


A set of equipment (servers, computers, storage devices, and printers), shared data folders, a list of authorized users, and a set of security policies in a private network system all managed by one administrator and/or delegated administrative teams. The administrators can set up and remove user accounts, reset passwords, configure permissions on shared folders and printers, and control configuration of the computers in the domain. Generally, a given company or agency will have their entire network organized under one domain, unless security or legal requirements call for separation.

domain name

The name of a private network domain (such as a Windows Active Directory domain), the name of a web site (as in, or the part of an e-mail address after the recipient's name (following the @ sign).

See also: DNS, domain, Active Directory


To transfer a file (such as a new program, document, photo, or video) from another computer or web site to your computer. Or, more generally, inbound communications from the Internet to your computer or network.

See also: upload


See: device driver


A hardware device that reads from, writes to, and erases data storage media, such as disks or tapes. Examples include a hard drive (with disks permanently fixed inside), floppy disk drives, CD or DVD drives, and tape drives. Also refers to a USB thumb drive.


Acronym for digital subscriber line, a technology developed in the 1990s that now allows faster transfer rates over ordinary telephone lines than the older T1 system for less money, but with limitations on how far your home or office can be from the phone company's routing station which T1 did not have.

See also: T1, cable internet


See: digital video disc


This is a general term typically referring to anything, such as configuration parameters, that can change during operations.

dynamic DNS

This is a capability of some DNS servers that allows a computer using a dynamic IP address to update the DNS server's lookup records automatically with its new IP address when the computer's IP address changes. This can be useful if you have a dynamic IP address and need others to be able to find your computer by its host name through DNS.

See also: DNS, dynamic IP

dynamic IP

An IP address assigned by your Internet access provider when you connect your router or computer to the line (DLS, cable modem, etc.) that can be changed at any time by the provider. This is the default option when signing up for Internet access, and it's perfectly adequate if you don't run your own web or mail servers, and just need to access web sites from your office or home. It allows the Internet access provider to oversubscribe their allocated IP addresses, since a certain percentage of their customers are disconnected at any given time for whatever reason. Your IP address generally doesn't change unless you shut off your modem or router for a while and then turn it back on; even if it does change while you're actively using your Internet connection, in most cases you will not even notice.

See also: static IP


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1. A type of device that sits on the border between two networks; for example, a router that connects a large private network to the Internet.

2. A generic reference to latest version of a given piece of software or data definition schema.


The ability of server hardware or software to increase capacity in a short amount of time to meet a large spike in usage. This generally applies to high traffic websites or other online services accessible by the public, running in virtual machines on a cloud infrastructure. Elasticity is implemented by provisioning more instances of the required server virtual machine from its original template, which increases the hourly cost payable by the website owner to the cloud provider. These new instances will access the same shared databases as the existing virtual machine instances, and help respond to visitors quickly. Once the traffic spike has passed, the extra virtual machines can be shut down.

See also: scalability, cloud, virtual machine


One of the oldest services on the Internet, enabling personal messaging between individual users. Offers longer and richer messages, attachments, and better long-term storage and sorting of received and sent messages, than instant messaging or SMS.

See also: instant messaging (IM), SMS

e-mail server

This is a computer that sends and receives e-mail on your behalf. When someone sends you an e-mail message, it gets delivered to your e-mail server right away, and is stored there until you retrieve it either by logging on to a website (if you use webmail), running e-mail software (such as Microsoft Outlook) on your computer, or viewing it on your mobile phone. If you see an option in an e-mail program on your computer about leaving the mail on your server, this determines whether your program clears the messages off the server once they have been transferred to your computer, or leaves them there so you can access them again from another device.


The process of scrambling a file stored on a computer, or any information sent from one user to another, so that only the owner or intended recipient can unscramble and view the information. This process typically uses a password or cryptographic key, which is mathematically integrated into the encryption process and therefore required to decrypt the data.


A user device that runs apps and accesses the Internet, such as desktop computer, laptop, tablet, or smartphone.


Acronym for enterprise resource management. A broad term covering any database system that assists in management of business operations, most significantly supply chain management and manufacturing systems. It covers aspects such as inventory, procurement, quoting, warehousing, and asset management. The most comprehensive implementations integrate customer relations, financial reporting, and human resource management. This is usually a major application that is implemented as a special project along with significant investment in new hardware and training; it's not generally a software application you can just buy and install, like typical desktop software. Examples include Oracle's E-Business Suite, and ECC by SAP, which typically run on a mainframe.

See also: CRM, HRMS


A general term referring to any problem that causes a computer not to do what the user expects, regardless of the cause. Errors can be caused by a fault in the program itself (bug); misconfiguration of the system; lack of training or understanding on the part of the user; hardware failure due to poor engineering or overheating, poor network connections, etc.; or transient conditions caused by pushing a program or the computer beyond what it was designed to do (such as running too many programs at once or creating excessively large data files).

See also: bug, crash


This is a broad term, applied to many of the custom systems recently designed to acquire a signature using e-mail or on a website, instead of more traditional postal mail or fax. Methods vary widely, from having the user draw his signature with a mouse, to typing secret codes tied to the signer's e-mail address, to just having the user type his name in a box.

See also: digital certificate


The most common system by which computers on a local area network communicate and manage traffic amongst themselves. Although originally a trademark of its inventor, the Xerox Corporation, the term is now used to reference the networking system itself, which was defined as an international standard in 1980.

See also: Xerox


A type of file that contains program code, as opposed to text, graphical, or numerical data. Any program, application, or other function you use on your computer is driven by code in executable files. Your computer comes with many of these, and you add more of them whenever you install new software.

See also: document


To activate an application program on your computer, typically by double-clicking on its icon. Synonyms are "run", "open", and "launch". Technically, this means the program code is copied from the hard drive or website into your computer's transient memory (RAM) for direct access by your microprocessor so the program window can display on the screen, accept your input via the keyboard and mouse, process data, and do your work.

See also: install


A network communication sent to a target (such as a computer server, workstation, or network device) that is specially designed to take advantage of a fault in the software on the target that handles network communications, in order to intrude into the target or simply cause it to crash. A common example is a buffer overflow attack.

See also: buffer overflow, intrusion


1. In relation to files stored on your computer, this is the three or four letters following the main portion of the filename, which, by convention, describes the file type (such as whether it is a file containing a photo, ASCII text, an executable program file, or a spreadsheet).

2. In relation to web browsers, this is a piece of software added to the browser to allow better interaction with a web site, or more functions and features within the web browser program itself. In the Microsoft Internet Explorer browser, extensions are called ActiveX Controls.


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fault tolerance

A method of designing computers, networks, and storage systems to allow them to withstand spontaneous hardware component failure with no downtime. A common example is installing multiple hard drives in a server which duplicate all the data between them, so that if one fails, the server continues to operate running on the extra hard drive. A broader example, particularly for a company that uses its IT systems to provide 24/7 services over the Internet, might involve having multiple connections to the Internet using different providers. By itself, fault tolerance does not address faults caused by software errors or database corruption.

See also: high availability, disaster


A process by which partner IT systems are configured, by agreement between the system owners, to authenticate user logins through a central authentication provider. In other words, a user logs in with one account and credentials (such as a password) to a computer or web-based application, and from there can access other systems within the federation without having to provide credentials, or even being registered into the system prior to signing in for the first time. This requires coordination and technical configuration on the part of the system administrators. But, this simplifies collaboration between these systems, and improves the ability to monitor and control user accounts and access to enterprise data and applications that may be spread out on different domains, in addition to the benefit of a single sign-on experience for the users. Examples include a Wi-Fi hotspot that has users sign in using a LinkedIn account to gain access to the Internet, or a political opinion site that has users sign in with a Facebook account to post a comment. Another example is a parts supplier that allows access to their secure ordering website by purchasers that were authenticated and authorized by the purchasers' IT systems. When a new person at a purchasing company wants to log in, the supplier doesn't have to create a user account, or have the user self-register, on the supplier's system. An authorized user can get into the supplier's website just by logging in to a computer on purchasing company's network with a valid user account on that network.

See also: single sign-on


A type of network cabling made of extremely thin, flexible glass tubes, which uses light beams to transmit data instead of electrical waves used by every other kind of transmission medium. It allows for extremely high speed communications over very long distances. Large organizations use it only when they need very high-speed, secure links between geographically separated facilities, because it is tremendously expensive to install and maintain. The core routing infrastructure of the Internet runs on fiber. Also, since fiber is impervious to electromagnetic interference, you might find it in places where ordinary network cabling will not work, such as in a radiology lab.


A chunk of information saved under a unique identifer (location and file name), which can comprise a simple document, part of a database, or some program code. A file, whatever its type, is always identified by both its name and location in the directory/folder hierarchy, so two files can have the same name if they are in different folders. Other information your operating system will track about each file may include its creation date/time, the date/time last modified, who owns the file, and who has permission to use it.

See also: folder


A security device that restricts network communications depending on all kinds of factors, such as the identity of the transmitting and/or receiving computer, the identity of the user, and the type of communications being transmitted. Most typically, it is used to protect against criminals gaining access to data and files on a home or business network from outside the network. Because of the wide array of capabilities that modern firewalls can now perform, a device simply called a "firewall" now generally refers to a device that blocks or allows traffic based on the network address of the transmitter and receiver and the type of each network packet, without examining the content of the traffic. Devices that examine the traffic are called next-generation firewalls or unified threat managers.

See also: next-generation firewall (NGFW), unified threat manager (UTM)


This is actually a trademark of Apple, but it has become a common term to refer to an IEEE 1394 interface. It is a type of port found on a computer, similar to USB. It was developed by Apple to be more suited for transfer of large amounts of data such as digital video.

See also: USB


Software that is embedded and generally fixed inside a hardware device, for the purpose of controlling the device's behavior and interactions with your computer. Only technicians typically have to deal with firmware.


A type of storage medium, typically used for storing personal data on a thumb drive, or embedded on thin plastic cards for use with digital cameras. Not to be confused with the trademarked name for the web-based animation software platform created by Adobe.

floppy disk

An obsolete storage medium, going back to the 1970s. It is a soft magnetic coated disk, inside a soft protective sleeve, which requires your computer to have a floppy drive to use. Original floppy disks were 8 inches in diameter, whereas the ones used with personal computers in the 1980s were 5.25 inches. A floppy disk can only hold a little more than one megabyte. In the late 1980s, they were shrunk to 3.5 inches and enclosed in a hard plastic case, but continued to go by the moniker of "floppy" disk. This caused a little confusion as hard disks came into wide use; a hard disk is a completely different type of storage technology, but sometimes people incorrectly thought this term referred to the 3.5-inch floppy disks in a hard case while the term "floppy" only referred to the older, soft 5.25-inch disks.

See also: hard disk


Windows and Mac OS term for a container of documents, programs, and other files; usually displayed graphically as a manila folder, which will show a set of icons for the files inside when opened. Folders can be nested; that is, you can create folders within a folder, each with its own set of files and/or subfolders. In the UNIX world, a folder is called a "directory".

See also: file


A computer industry term for what the publishing industry calls a typeface. For any given font to display properly, your computer must have the files containing the font data, which comes separate from the document file that contains the text itself. Font data can be embedded inside document files. Some font files are copyrighted by the designers of the fonts, requiring you to pay license fees to use them in artistic creations, embed them in documents, or even have them on your computer.


In disk storage, formatting a volume means erasing its current contents and installing the indexes and directories needed to save files to the volume.

See also: volume


Acronym for Fully Qualified Domain Name. When using the Domain Name System (DNS), this means a host name of a particular computer is given along with its domain name up to the root of the DNS hierarchy.

See also: host name

free software

1. In the common sense, this refers to software that you can download without having to pay for it. Examples include both proprietary and open-source software, which includes everything from operating systems, hardware drivers, web browsers, media players, and even full office application suites.

2. An alternative (and confusing) meaning of the word, promulgated by Richard Stallman and his Free Software Foundation, refers to open-source software that is distributed with legal terms that prohibit incorporating the source code into propietary software (meaning, any derivative works must remain open-source), and which allow the software to be redistributed for free if the recipient wishes. This has nothing to do with the price of the compiled software, which may be sold at any price by a developer who has modified, assembled, and improved free software. A high-profile example of free software sold for a price is Red Hat Linux. Red Hat charges for its distribution of the open-source operating system GNU/Linux, and in return provides a neatly compiled and thoroughly tested package including the operating system and custom utilities, technical support, and automatic updates.

See also: open source, Richard Stallman, Free Software Foundation


Acronym for File Transfer Protocol, one of the oldest systems of file-sharing on the Internet. It enables you to connect to another computer, then browse, download, and/or upload files. It should only be used for trivial transfers or downloads of programs that are freely available anyway, because it is no longer considered a secure method of sharing files in our more sophisticated age.


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Acronym for Graphics Interchange Format. A type of computer file that stores a photo or other graphic image in a compressed format, with no loss in quality, intended for display on a computer screen. The file format also supports simple animation. This was originally developed by CompuServe, once a major Internet Service Provider, to improve transmission speed of pictures over slow modem connections. This format is more suited for line art (cartoons) than actual photographs, because of its limited color palette.

See also: bitmap, JPEG, PNG


This term usually always will refer to exactly one billion bits, and is used in measuring transmission speed of digital communications (which sends all data one bit at a time or in groups of bits). Current local area networking equipment transmits at 1 gigabit per second, over copper wires within your building. For external communications, currently only optical (fiber) connections are fast enough to be measured in gigabits; for example, OC-192 runs at 10 gigabits per second.

See also: bit, kilobit, megabit


Either exactly 1,073,741,824 bytes or 1,000,000,000 (1 billion) bytes, used for measuring file size or storage capacity. Because computers count in twos, 1,073,741,824 is a round number to computers. But, since we think and notate numbers in tens, written documentation or or even technical specifications of file sizes or storage capacity sometimes use the term gigabyte to mean 1,000,000,000 bytes.

See also: byte, kilobyte, megabyte, terabyte


Acronym for GNU General Public License. The written terms published by the Free Software Foundation that are applied to software developed by the GNU Project, and therefore to any derivative works. The GPL provides that the software will remain open source, and any modifications and redistributions may not be incorporated into proprietary software. The GPL is not restricted to software developed by the GNU Project; any developer of any software may incorporate the terms of the GPL into his work, if he wants to assure his software and all derivative works will remain open-source. There are many other types of similar license agreements, such as LGPL, the Apache License, BSD, Share-Alike, etc., and anyone can write their own, but GPL is among the most well-known that many developers simply slap on to their projects.

See also: Free Software Foundation


An IT equipment installation project where no equipment or infrastructure already exists, and accounting for or maintaining compatibility with standards are not required. This essentially means a new IT system built from scratch. This term also applies to a software development project lacking such constraints.

See also: brownfield


An internal e-mail, scheduling, and data sharing system run within a company, such as Novell GroupWise, IBM Lotus Domino, or Microsoft Exchange Server.

See also: Exchange Server, GroupWise, Lotus Domino


Acronym for graphical user interface. A system wherein you operate your computer by clicking on menu items and icons to open programs, move or delete files, and set options. This is the current standard.

See also: command-line interface


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A clever and inquisitive computer user who digs into the inner workings of computers and network systems to gain detailed literal understanding of the system, and discover functionality of computers beyond what they may have been designed to do, as well as flaws to be addressed. While some hackers break the law with their activities, the term "hacker" is not intrinsically derogatory. All positive computer innovations were derived, to some extent, from the work of hackers.

hard disk

See: hard drive

hard drive

An internal component of personal computers and laptops, which stores the operating system, all application programs it came with or that have been installed, and all your data. This is the fastest and most accessible location for stored information, which will persist on the drive even after the computer is powered off, since it is stored on magnetic or solid-state media. It is often called the "C drive", since the most common personal computer operating system (Microsoft Windows) always assigns the letter C as an alphabetic identifier to your computer's primary internal hard drive. External hard drives that plug in to a port on your computer are available, but generally you only put your personal data on there and not your operating system or programs. Some people incorrectly use the term "hard drive" to refer to a desktop computer itself.


Physical equipment, including computers, mobile devices, monitors, peripherals such as keyboards and mice, and printers, as well as network routing and communications equipment, and the internal components of each of these. When a problem is determined to be a "hardware problem", for example, this means no amount of reprogramming can fix the problem, and components will need to be replaced.

See also: software


See: hyperconvergence


A system of storing files or other pieces of information in containers, which can also be stored inside other containers. An example is the file system on your computer, where you can have folders, which can contain subfolders, which can contain more subfolders, and so on. Each folder at any level can contain files where your actual information is stored.

See also: file, folder

high availability

A method of designing computers, networks, storage systems, application software, and databases to allow applications and databases to be recovered quickly after spontaneous hardware component failure, software errors, or database corruption. A common example is virtual machine clustering, which involves having spare physical servers; if one physical server fails, all of the virtual machines that were running on that server will reboot on another server, restoring service within a few minutes.

See also: fault tolerance, disaster

home page

The web site your web browser opens automatically when you launch the web browser.

hosted service

Information, computing, messaging, or data storage services provided by an outside company on servers not owned by the customers, and accessible via the Internet. The services and data may be accessible only by the customer of the hosted service provider (such as file storage and collaboration services for mobile users within a given company), or for the public in general (such as a web site).

See also: on-premises, cloud

host name

The unique name of a particular computer, printer, or other device within a networking system. On the Internet, which uses a system called the Domain Name System (DNS) to locate computers, the term "domain name" is often used interchangeably with "host name".

See also: domain name


See: patch


A location where access to the Internet via Wi-Fi service is provided, either for free (such as in a coffee house), or for a fee (usually per hour or day, such as in a hotel or airport). Some cell phones can be set up as a "personal hotspot", where the phone connects to the Internet via its cellular service, while providing a Wi-Fi signal for you or others to connect to the phone and on to the Internet using a laptop.


Acronym for human resources management system. Database system designed for business to manage its employees. The most well-known of these was PeopleSoft, now owned by Oracle.

See also: CRM, ERP


Acronym for Hypertext Markup Language; the underlying format of a standard web page. Each time you access a web site, the web server sends the content as an HTML file; your web browser then interprets the HTML in the file and displays the page on your screen. The HTML file includes the text of the web page, formatting and screen layout information, pointers to photos and animations, sections with program code, and links to other web pages.


Acronym for Hypertext Transfer Protocol; the set of rules governing how your browser makes requests to a web server to retrieve a web page, to send information (such as when you fill in a web form or upload a file), or to download files as an alternate method from older protocols such as FTP.

hybrid cloud

An IT system comprised of private cloud and public cloud resources. The private cloud provides high performance and control, whereas the public cloud portion can serve as extra capacity for the private cloud when there are spikes in demand for services, or may be deployed to routinely serve users who cannot reach the private cloud as easily, such as those in a foreign country.

See also: cloud


This is mostly a marketing term by vendors of private cloud systems, describing convergence of all components of the modern data center (virtual servers and desktops, storage, networking, management software, and security) into a single product. Also may be called converged infrastructure (CI) or hyperconverged infrastructure (HCI).

See also: convergence


A link in a hypertext document.


A special type of document for display on a computer screen, which has clickable links to other relevant documents or other resources, either on the same computer or on other computers on your network or on the Internet. The address information of each link is embedded in the document, but not necessarily displayed. Of course, hypertext is a fundamental component of web pages, but it has been around for much longer than the web, mostly in database lookup systems like repair manuals, online help systems, or other technical document sets. Today, you will find hypertext in virtually every computer application, even in places that you wouldn't expect, such as word processing documents intended for printing.


Software that starts up and manages virtual machines, and arbitrates access to processor time, RAM, disk space, and network connections. The hypervisor manages moving a virtual machine from one physical server to another, and advanced hypervisors can do this without interrupting service. Major vendors of hypervisor software include Citrix, VMware, and Microsoft. Parallels is a well-known hypervisor for running a Windows virtual machine on a Mac.

See also: virtual machine


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IEEE 1284

See: parallel port

IEEE 1394

See: FireWire


Acronym for Internet Message Access Protocol; a method by which your computer can access e-mail addressed to you that has been delivered into your mail system. Similar to webmail, IMAP is more suitable than POP3 for mailboxes shared between multiple users, or for one user accessing the same mailbox from different computers/devices. All IMAP systems use version 4 of the protocol, so often you will see it referred to as IMAP4.

See also: POP3, web mail

information security

A business process that protects information assets and the business functions that rely on them. These assets include the intangible value of the intellectual property, as well as physical information, particularly the information technology system.

information systems

The overall business processes involved in collecting, storing, controlling, organizing, analyzing, manipulating, and transmitting information, including non-technical aspects such as marketing, research, legal, and human resources policies.

See also: information technology

information technology

Electronic equipment, including hardware and software, which is designed, programmed, and deployed to support information systems.

See also: information systems


A type of printer technology that sprays microscopic droplets of ink from ink cartridges onto the page. It is a very inexpensive method of printing, but is less suited for pure black-and-white printing than laser technology.

See also: laser


To copy program files and configuration data for an application program or device driver to your computer's hard drive, and modify any settings in your operating system that may be required for the program to run properly. Usually, the program files come on a CD or DVD, or can be downloaded directly from a website, along with an "installer" program that performs all the tasks of copying the files to their proper locations, setting up shortcut icons, generating configuration data based on what type of computer you have and your answers to questions it might ask about various options, and making necessary changes to your operating system.

See also: execute

instant messaging (IM)

A system where two users on different computers, running compatible software, can find each other and type messages back and forth in real-time, as opposed to ordinary e-mail. Unlike SMS, which relies on a network designed for cell phones, IM uses regular computer networking communications methods, so the length and content of messages are not as limited as SMS.

See also: e-mail, SMS

integrated circuit

A single wafer of silicon in which various types of transistors have been microscopically etched into the surface. The transistors can store data or perform mathematical or logic functions using electricity. All modern electronics use integrated circuits, the latest of which can fit billions of transistors and tremendous computational capability into a thumbnail-sized wafer. While more expensive to develop, an integrated circuit is much more suitable for mass production than a discrete circuit (where the transistors are separate physical devices connected by wires), and can scale to complexity and power far beyond what is possible with a discrete circuit.

integrated solution

As set of technology hardware, software, and/or services planned and implemented via high-level planning, in order to apply to and encompass the entire IT system.

See also: solution, point solution


An information security term referring to protection of information from corruption or other unauthorized changes, either where it is stored or in transit. These can be caused by hardware or software malfunction, or by malicious users who may be able to alter data even if they can't see it.

See also: availability, confidentiality, corruption


A communications infrastructure whereby individual users or computers on separate networks may communicate and share information. The largest in the world is, of course, what we simply call "the Internet", but which was originally called ARPANET when under development by the U.S. Department of Defense in the 1960s.

See also: intranet


An emulation of typical Internet services, such as a collection of websites or an e-mail system, that are available only to users within a private organization. This is a loosely defined term relative to the others on this page, so you may find different IT service providers or organizations with slightly different understandings of the meaning of this word.


A situation where a user, with automated programs or by working real-time at his computer, performs functions on a computer or network system that he is not permitted to perform. Such functions include reading or modifying document files or databases, causing a computer or server to crash, stealing passwords, sending junk mail from the victim's system, causing ads to appear on a victim's screen, and installing software that encrypts the victim's files and demands ransom. Intrusion can be achieved by sophisticated means such as sending specially designed network communications to exploit a fault in the target system, by tricking a user into running a program that allows the unauthorized access, or simply by guessing a password.

intrusion detection system (IDS)

Software that identifies potential or actual intrusions by examining network traffic for exploits, and alerts the system administrator to take any necessary action to defend the system. This runs on a computer or device connected to the network where it can see all network traffic for analysis. Compared to a network-based intrusion prevention system (NIPS), an IDS requires less sophisticated software and hardware, and is less disruptive to implement, since it does not analyze the network traffic in real-time. But, since it relies on the administrator to figure out how to protect the network after an event is raised, we can expect that exploits would be more likely to pass compared to a properly-configured IPS.

See also: exploit, intrusion prevention system (IPS)

intrusion prevention system (IPS)

Software that identifies potential or actual intrusions and automatically blocks the intrusion from occuring. There are two types:

1. A network-based IPS (NIPS) works by examining network traffic for exploits, and blocking communications as needed to prevent the exploit from succeeding. This generally runs on a device between potential attackers and the protected computers (meaning, of course, on the Internet access gateway or firewall). Compared to an intrusion detection system (IDS), a NIPS requires very fast hardware and sophisticated software to be able to analyze the traffic and make a decision in real-time. Also, since it takes automated actions that actually affect network function (as opposed to only raising an alert as an IDS does), an IPS can be very disruptive if not configured properly, or if it simply generates many false positives.

2. A host-based IPS (HIPS) is software that runs on a computer or network device (the host) and examines everything the host does, blocking activities that may be the result of an intrusion. This is generally only seen on heavily managed enterprise networks, because it is much more complex than typical anti-virus software, and requires extensive configuration and continuous management to be useful in protecting the host without making the system difficult to use.

See also: exploit, anti-virus

IP address

A numerical identifier your computer uses to communicate on your network or over the Internet. Depending on how you access the Internet, your IP address can identify your computer, or at least the building your computer is in, which could (when combined with other information about you) be used to link you to your activities over the Internet.


Acronym for Integrated Services Digital Network. Developed in the 1980s but with roots back to the 1960s, this was once the standard for providing feature-rich digital telephone service. It could support dozens of simultaneous distinct phone lines and data services over one telephone wire running out of your building, and it provided features otherwise unavailable back when it was first developed, such as direct-inward-dial to an extension, caller ID, data file transfer, video conferencing, and high-speed digital dial-up data links. VoIP, and even some innovations in standard analog phone service, have rendered ISDN virtually obsolete in the telephone world. ISDN also was once commonly employed to establish long-distance communications links between private networks on an as-needed basis, such as uploading sales data from a branch to the headquarters every night with a modem similar to a regular dial-up modem, but at 128 kilobits per second; this has been superseded by VPN over the Internet. However, many systems in the broadcast industry use ISDN today for long-distance transmission of live audio/video, because transmissions may be interrupted when using a VPN through the public Internet, as opposed to the fixed circuits of the separate ISDN network.

See also: T1, VoIP, VPN


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Acronym for Joint Photographic Experts Group (often shortened to JPG), which refers to a computer file format for saving photographs in compressed format, with only a small loss in the quality of the picture. This is much more suitable for photos than the older GIF format.

See also: bitmap, GIF, PNG


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The core software of an operating system. All other software (such as modular device drivers, system utilities, and user applications) depends on functions performed by the kernel.


This term usually always will refer to 1,000 bits, and is used in measuring transmission speed of digital communications (which sends all data one bit at a time or in groups of bits). For example, common modems in the 1990s operated at 28.8 kilobits per second.

See also: bit, megabit, gigabit


Either 1,024 bytes or 1,000 bytes, used for measuring file size or storage capacity. Because computers count in twos, 1,024 is a round number to computers. But, since we think and notate numbers in tens, written documentation or or even technical specifications of file sizes or storage capacity sometimes use the term kilobyte to mean 1,000 bytes.

See also: byte, megabyte, gigabyte, terabyte


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Acronym for local area network. A system of interconnected computers within a single room or building. This is a term that many IT professionals use to refer to computer communications within your office, as opposed to your phone system or anything outside your office (such as the Internet).

See also: network, WAN


A computer that has an LCD screen, keyboard, speakers, some sort of substitute for the mouse, and a battery all built-in to the unit for portability.

See also: desktop, notebook, tablet, ultrabook


A type of printer technology that impresses toner onto the page and melts it into the paper fiber by applying heat as the paper rolls through. It does not produce as rich colors as inkjet technology can, but the crispness of the output is far superior, making it more suitable for black-and-white document printing.

See also: inkjet


See: execute


Acronym for liquid crystal display, the technology behind modern flat-screen computer monitors and television sets, which replaced CRT monitors in recent years for desktop computers. It has been used in laptop computers since their inception in the early 1980s.

See also: CRT


The timeframe for managing information technology assets. The stages include pre-acquisition specifications and requirements, lab and/or pilot testing, migration from outgoing assets, deployment, user training, maintenance and performance monitoring, replacement, and disposal. This can apply to individual information technology assets (specific hardware, software, or data), or a solution including a combination of these.

See also: solution

list box

A selection list in an application program or web page that requires you to select only from the items already in the list, either using the mouse or the arrow keys on your keyboard.

See also: combo box


See: install

log file

1. A file generated by computer programs recording events, status reports, and errors. Each line of a typical log file records the date and time of the event, the device or program affected, and what happened. Log files are either in plain text format for human administrators to read through, or some kind of a binary format. To read a binary file, an administrator must use a log viewer program that is capable of reading that particular type of log file. But, binary log files are more amenable to automated parsing and analysis by management and auditing software, which is especially useful when there are millions of log entires.

2. Sometimes the files making up a database transaction log are referred to as log files.

See also: plain text, binary, auditing, transaction log

log in / log on

The process of entering your credentials (usually a user name and password) to identify yourself for the purpose of gaining access to secured services and data. The terms "sign in" or "sign on" mean the same thing.

log out / log off

The process of ending your work session with a system, so as to prevent anyone else from gaining access to secured services and data only you should access, and to free up resources for other users. The terms "sign out" or "sign off" mean the same thing.

lossless compression

A method of compressing data so that when it is decoded, every last bit of information is restored and the file is exactly as it was before compression. This must be used when a binary program file, or any kind of document (such as a spreadsheet or text document) is to be compressed (to save disk space or reduce transmission time).

See also: compression, lossy compression

lossy compression

A method of compressing data so that much greater compression is achieved (that is, a smaller file) compared to lossless compression, but at the cost of some loss of detail in the original. This is used for music files (such as the MP3 format) and images (such as GIF or JPG), where the loss in detail will be virtually imperceptible to the human ear or eye. It cannot be used for files which would become corrupt if modified, such as user data files (spreadsheets and documents) or binary program files.

See also: compression, lossless compression


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MAC address

A serial number assigned to your computer for communications on a local network. It is only used for local transmissions, and only visible to computers and network equipment to which your computer is directly connected through in the same LAN segment. Since the MAC address includes a manufacturer's identification code, every MAC address in the world is unique. In this context, MAC is an acronym for Media Access Control, not to be confused with the brand of computers produced by Apple, the Mac.

See also: IP address


A type of storage that uses magnetic fields on a physical surface to store data. Still in wide use with inexpensive conventional hard drives (as opposed to cutting-edge SSD drives), as well as older technologies such a backup tapes or floppy disks.

See also: optical, SSD


This term is sometimes incorrectly used for an ordinary server in an office LAN. But it only properly refers to a computer system specially designed for high-volume business transaction processing and storage, and extremely high-volume input/output for simultaneous access by hundreds or even thousands of users. The mainframe has been around commercially since the 1950s, and was and still is almost exclusively in the IBM domain. An example of interacting with a mainframe might be at the ticket counter of an airline, at a bank, or at the point-of-sale terminal for a major national retail store.

See also: IBM

malicious software

See: malware


This is a general term for any kind of malicious software such as viruses or spyware, that runs on your computer to do damage, such as disrupting your work, forcing your computer to open websites the program chooses, or steal your personal information and send it to a criminal. Malware gets installed on your computer either through technical faults that allow another computer to just push it onto yours, or through various methods of getting you to unknowingly install it yourself.

See also: adware, spyware, anti-virus


This term usually always will refer to exactly one million bits, and is used in measuring transmission speed of digital communications (which sends all data one bit at a time or in groups of bits). For example, a typical DSL speed today operates at anywhere from 1 to 5 megabits per second. Most older local area network equipment communicates at 100 megabits per second using copper wires. Current local wireless networking generally runs around 50 to 100 megabits per second. The latest cellular networks can support transmissions from 1 to 10 megabits per second or more.

See also: bit, kilobit, gigabit


Either 1,048,576 bytes or 1,000,000 bytes, used for measuring file size or storage capacity. Because computers count in twos, 1,048,576 is a round number to computers. But, since we think and notate numbers in tens, written documentation or or even technical specifications of file sizes or storage capacity sometimes use the term megabyte to mean 1,000,000 bytes.

See also: byte, kilobyte, gigabyte, terabyte


This term properly refers to RAM (and vice-versa), but it is often mixed up with storage.

See also: RAM, storage


Early name for what we now call a personal or desktop computer—a single-user system based on microprocessor technology pioneered by Intel. The name was derived both because of its reliance on the microprocessor, and as a way to denote a type of computer that was smaller than the minicomputer. Today, mainframes are not nearly as big as they once were, minicomputers no longer exist, and even multi-user servers and high-performance web servers are based on microcomputer technology. So the term "microcomputer" is no longer necessary.

See also: Intel, microprocessor


The central electronic computational device in any tablet, laptop, personal computer, server, or modern mobile phone; more specifically, a single silicon chip package using integrated circuit technology, designed to carry out a full range of computing functions through custom programmability. Prior to the successful creation of the microprocessor by Intel in the early 1970s, computer chips only carried out a limited set of specific functions, either requiring a hodge-podge of chips, or one very expensive custom-designed complex chip. The invention of the microprocessor led the way for the production of personal computers within a few years. Intel now refers to their microprocessors simply as "processors".

See also: Intel, integrated circuit


Obsolete precursor to the microcomputer; comprised of a generation of computers that, when introduced in the 1960s, were significantly smaller than the mainframes of the era due to different architecture and lesser performance requirements. They typically ran VMS or UNIX operating systems, and disappeared in the 1990s.


An exact duplicate of data for either fault tolerance or performance. An example of fault tolerance is a server with two mirrored hard drives, where everything on one drive—the boot files, operating system, software, and data—is duplicated on the other drive exactly; if one drive fails, the system will keep running. An example of mirroring for performance includes file hosting sites for major software distributions that are downloaded by the public in high volume. Each site has the same copies of the software available for download, and customers can pick the closest one geographically for the fastest download. The software's publisher will generally have a list of the mirror sites on its website, or may have systems in place (such as for software update programs) that already know where all the mirrors are, and will pick the closest and/or least busy mirror automatically.


A device that enables computers to transmit over analog communications systems, such as the telephone network or cable television wires. The term "modem" by itself refers to the device that would pick up your phone line, listen for a dial tone, and call your Internet provider's modems to access the Internet, or directly to a bulletin board or other online system (many years ago). Modern DSL modems communicate with analog signals mostly outside voice range, so you can talk on the phone while connected to the Internet via DSL. A cable modem likewise communicates over cable TV wires without disrupting your TV signals. DSL modems and cable modems these days are usually also combined modem/network devices, which perform computer networking functions such as sharing your Internet connection with multiple computers, and performing routing and firewall functions.


A computer's video screen. This is somewhat of an obsolete term, left over from very early computing days when computer programs were so simple, and display capabilities so limited, that most program output to the screen was for the purpose of "monitoring" the program's progress, rather than for manually manipulating data, composing documents, playing games, etc.


This is a major component inside a computer, which connects and controls interaction between all the internal components. Your processor, RAM, and hard drives plug directly into the motherboard.

See also: microprocessor, RAM, hard drive


A popular format for storing and transferring music tracks on computers and into portable MP3 players, which replaced CD players and tape players at the end of the 1990s.

multi-factor authentication

A process by which a user proves his identity (for the purpose of logging in) using more than just a user name and password. The three types of factors: something the user knows (such as a password), something the user has (a key), or proving presence of the user's physical body (retina scan, fingerprint, or voice/face recognition). The most common example in information technology is a key card (what the user has) with a PIN (what the user knows). For cloud services, this is commonly implemented with the usual password (what the user knows) and a verification message sent to the user's mobile phone (what the user has).


A term that arose in the early 1990s, when the ability to play music and videos was just becoming available on personal computers. Until then, the only output medium for computers were static images on screen or on paper, so what we take for granted now had its own catch-phrase to describe these novel dimensions in personal computing.


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A collection of computers and other electronic devices that communicate with each other to share common functions and/or data.

See also: LAN, WAN, intranet, internet

next-generation firewall (NGFW)

A marketing term, appearing around 2007, that originally described firewalls targeted for the enterprise market, that perform application- and context-aware intrusion prevention in addition to the conventional function of blocking or allowing traffic based on network address and packet type. These originally left out junk mail blocking, anti-virus scanning, and website filtering, to keep the device from slowing down traffic and keep down the price, given their target market may have hundreds or thousands of users and generally had junk mail, anti-virus, and website filtering systems in place already. But, many NGFWs currently in production have added all these features due to advances in processing speed, and some products are clearly now targeted to the small/medium business market, blurring the distinction between NGFW and UTM.

See also: firewall, unified threat manager (UTM), intrusion prevention system (IPS)


A loosely defined term, which generally refers to a particularly small laptop computer.

See also: laptop, tablet, ultrabook


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A relatively new term referring to servers owned by a company and located at that company's site. Until recently, all business IT systems consisted primarily of on-premises servers, so they were simply called their "servers". In the current era, many companies (even large ones) now frequently do their internal work over the Internet on cloud services providers' systems, such as saving and sharing document files; storing users' mail, contacts, and calendars; and running internal database applications. As a result, the term "on-premises" has become more prevalent along with the need to differentiate services running in-house vs. in the cloud.

See also: cloud, hosted service


1. Data that is readily accessible. For example, data you can access on your hard drive is online, whereas data you copied to a tape and put on a shelf is offline. In common use today, though, this term refers to information accessible over the Internet, while anything not on the Internet, even though it is accessible immediately on your computer, is not considered "online". Here is an illustration: Before the Internet era, when computers were standalone devices, the term "online help" referred to program tutorials that were accessible from within a program by clicking a "Help" button, as opposed to printed in a bound paper book. Today, all programs have tutorials integrated into the program, so the term "online help" now refers to additional and more up-to-date information accessible on the Internet.

2. An active network connection, such as to the Internet generally, or to a specific network service.

open source

This term applies mostly to software for which the underlying architecture, design, and program instructions (the source code) are available without typical copyright restrictions, allowing software development companies or individuals to customize it for internal use, or even to package and resell it as a commercial product without paying royalties. As a result, open-source software is often available in many different variations from different publishers, and often free of charge.

See also: proprietary, free software, Richard Stallman

operating system

The software that provides your computer or mobile phone its personality and capabilities. From the user's point of view, the primary functions of the operating system are management of programs (installing, uninstalling, and shortcuts), management of documents and databases (sorting, searching, renaming, deleting, backup, and restore), as well as integration of peripherals (printers, scanners, storage devices). The operating system itself consists of a kernel (core), and non-kernel components and utility programs. Examples of operating systems for computers are Microsoft Windows, Mac OS X, GNU/Linux, and FreeBSD. Examples of operating systems for mobile phones are BlackBerry OS, iOS, Symbian, Windows Phone, and Android.


1. Recording technology that uses light to change the color of the recording medium and can then read back the data by measuring the wavelength of reflected light. An example of optical recording is a CD-R or DVD-R disc.

2. Communications technology that sends data as light waves through fiber cabling, as opposed to electromagnetic signals.

See also: magnetic


Automation of interdependent tasks at the level of information technology architecture; execution of a workflow involving different systems or applications, controlled by a software component in charge of the overall automation process. This occurs on a schedule, in response to a request by a user, or as a result of conditions observed by automated monitoring. An example is the provisioning of a virtual machine: processing, memory, and disk storage space must be allocated; the operating system installed from a template; login credentials configured; network connectivity established to the correct virtual network; security updates applied; and applications installed or additional configuration performed based on policies that apply to the user requesting the virtual machine, its location, and/or its purpose. The virtual machine is then registered with the administrative management system to enable activity logging and accounting for usage and billing, if applicable.


See: operating system


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parallel port

A mostly obsolete type of computer port, used primarily to connect printers. Also called IEEE 1284. This has been superseded by USB, which all desktop printers now use.


A continguous segment of a hard drive designated for a particular purpose. A hard drive might be split into partitions to support multiple independent file system volumes, either to separate different file sets, or to have the system volume of multiple operating systems present together on a single hard drive.

See also: volume, hard drive


A secret code you must enter to prove your identity to access protected resources, usually comprised of a single word, or a jumble of numbers, letters, and symbols (to avoid being easily guessed).


Functionally the same as a password, but comprised of a sentence or phrase (including spaces). You may hear this term in organizations that encourage users to try using passphrases rather than passwords, which will generally be harder for a criminal to guess or crack.


A small software package provided by the publisher of a software application or operating system, which updates components of an existing installation, to fix a bug in the software. Sometimes referred to as a "hotfix".

See also: update, upgrade


Acronym for Personal Computer. This was a trademark name for the IBM brand desktop computer introduced in 1981. In time, it turned into a generic term referring to all desktop computers compatible with the IBM PC architecture (as opposed to an Apple Mac). Today, it means any kind of desktop computer or even laptop (including the Mac), as opposed to a tablet or smart phone.


Acronym for Personal Data Assistant. This is the 1990s term for a handheld PIM device, such as the Palm Pilot or the Apple Newton. The term is no longer used, as the functions of PDAs are now included in modern smart phones.

See also: PIM, smart phone


Acronym for Portable Document Format. A universal computer file type invented by Adobe for printable documents that are intended to be broadly distributed through the Internet, requiring only free, simple PDF reader software to view and print, as opposed to more complex, editable word-processing files. Product brochures, manuals, technical guides, and government forms commonly use PDF.

See also: Adobe Systems

perimeter network

See: DMZ

personal computer

See: PC


Combination phone/tablet; a touch-screen smartphone that is so large it's as big as a small tablet. Most notable examples are the Samsung Galaxy Note series, the Nokia Lumia series, and now the Apple iPhone 6 Plus and BlackBerry Passport.

See also: tablet


Acronym for Personal Information Manager. This refers to an application or device that keeps address and phone lists, a calendar/scheduler, to-do lists, and a memo pad. A pioneering PIM device was the Sharp Wizard, released in the late 1980s, which was the size of a calculator and had a full alphanumeric keyboard. Most PIM devices came with software to manage the information from your PIM on a regular computer, such as Palm Desktop software for Palm devices, and BlackBerry Desktop Manager for the BlackBerry. Microsoft Outlook was a popular PIM application program for personal computers, and is still in use today, although calling it a PIM these days is archaic.

See also: PDA, sync


Acronym for Public Key Infrastructure. A database and set of servers managed by a trusted organization responsible for creating, distributing, and verifying the authenticity of digital certificates, which are used for authentication and encryption. For accessing secure websites or verifying most digitally signed e-mail, your computer uses certificates managed under dozens of PKIs administered by companies (such as VeriSign, Network Solutions, Thawte, Equifax, Comodo, DigiCert, and even several foreign companies) which have been designated as trustworthy by the developers of your computer software. For greater control and security, many companies institute their own internal PKI, managed by their IT department.

plain text

1. Another term for a text file.

2. Unencrypted information of any type sent over a network or saved on a hard drive which, if opened from the hard drive or captured in transit, would be easily read.

See also: text file, encryption


A piece of software you add to your web browser, to enable certain functionality on web sites you might visit that use the plug-in. An example is the Adobe Flash plug-in for the Mozilla Firefox web browser, which you must install to see Flash animation on a website you visit using Mozilla Firefox. This term is not generally used with the Microsoft Internet Explorer web browser.

See also: extension


Acronym for Portable Network Graphics. A type of computer file that stores a photo or other graphic image in a compressed format, with no loss in quality, intended for display on a computer screen. A successor to GIF, it supports a wider range of colors than GIF, but no animation. Still used mostly for icons and line-art. Although a photograph in PNG format looks as realistic as a bitmap, the JPEG format is preferred for photographs because JPEG can make a much smaller-sized file by reducing the picture quality in a manner that is almost imperceptible.

See also: GIF, bitmap, JPEG

point solution

An implementation of information technology hardware, software, and/or services to address a specific need, without considering whether or how the product integrates with the rest of the IT system.

See also: solution, integrated solution


Acronym for Post Office Protocol version 3; a simple method by which your computer can retrieve e-mail addressed to you that has been delivered into your mail system.

See also: e-mail, IMAP

power strip

A device with multiple AC power outlets that allows you to plug usually about six devices into one wall outlet. A power strip will almost always have surge protection built-in, but not necessarily. And, unless it has the words "battery backup" or "UPS" on it, then it does not provide any power on its own.

See also: surge protector, UPS

power supply

More properly called a power converter, this is a sealed box that draws AC power from the wall and converts it into DC power used by technology equipment. For desktop computers and large printers, the box is inside. For smaller devices like a USB drive, network switch, or laptop, the box is integrated into the power cord.

See also: UPS, power strip


A connection method used by some DSL providers that requires your modem or router to provide a valid a user name and password to connect.

private cloud

Cloud services built by a company using their servers, storage, and networking equipment in their own datacenter, typically to provide elastic and measured allocation of pooled resources to different departments within the company.

See also: cloud


A discrete block of program code that is running on a computer. This can be a user application, a background service program, or device driver.

See also: code


See: microprocessor


A set of instructions that your computer executes, as well as related configuration data to customize its operation. Inital power-up and self-testing, the process of loading of your operating system, the operating system itself, and every application you use, are all examples of your computer executing programs that are present on the computer. To create programs, software developers write the instructions using text-based syntax (this is called the source code), then use a program called a compiler to translate it into the binary format your computer will use to execute the program.

See also: source code, compile


In the computer world, this term usually applies to software for which the underlying architecture, design, and program instructions (the source code) are kept as trade secrets by the development company. Only the final machine-readable program files are provided to the user. Proprietary software is usually licensed for a fee per user or computer. Some proprietary software is given away for free (such as web browsers, or anything else that can be a delivery vehicle for advertising or otherwise generate income for the software publisher). Examples of proprietary software include operating systems from Microsoft, Apple, and Cisco; applications from Microsoft, Adobe, and Intuit; and server-based software packages from Oracle and IBM.

See also: open source


A shared set of rules used by computers, mobile devices, peripherals, network equipment, and software applications when communicating with each other. The rules specify how to set up communications; authenticate the users or devices involved; configure encryption; transfer messages, commands, and data; correct errors; and verify receipt of transmissions. Sometimes referred to as a "language" in other glossaries, but this is an inaccurate simplification. A given protocol works the same regardless of the language used in the underlying communications. A good non-computer analogy is how we use the telephone. To communicate by telephone, you have to learn the protocol first, which is: Look up the phone number; pick up the receiver; wait for the dial tone; dial the number; wait for the person to pick up and say "Hello" before you start speaking; and say "Bye" to indicate the conversation is complete before hanging up. If you fail to follow any part of this, you will fail to complete the communication, or at the very least cause confusion (if you hang up without saying "Bye", for example, the other party may assume the call was cut off and call you back to ensure the conversation was complete). These rules are all the same whether you're speaking English or Quechua.

proxy server

In highly-controlled networks, this is an intermediary computer you must go through to access a given service (usually the Internet). It is generally employed to block certain activities to enforce your company's Internet usage rules, and to perform caching.

See also: cache

public cloud

Cloud services offered by a service provider to customers on a non-exclusive basis, and hosted entirely on the service providers' servers, accessible via the Internet. Each customer's data, virtual networks, and virtual machines are separated from other customers.

See also: cloud

pull technology

A system by which a mobile device periodically requests new information from a server, such as checking for new e-mail every 10 minutes.

See also: push technology

push technology

Usually refers to an e-mail system whereby the e-mail server notifies the recipient's mobile phone when a new message has arrived, and then sends it. This prevents the phone from having to initiate a connection to the server every so often to ask if there is new mail, saving battery life on your phone when there's no mail, and enabling mail to be received instantly. All text messaging (SMS) systems work this way, and many phones support this with certain e-mail systems. Push technology is preferable to pull technology; pull technology is generally only used when push is not available.

See also: pull technology


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Acronym for Random Access Memory, or just "memory" for short. This is a component of your computer that determines how much you can have going on at a time—that is, how many files and programs you can have open on your screen. It is measured in megabytes or gigabytes. It is cleared any time your computer loses power or is simply restarted, and anything you did not save to your hard drive is lost. The terminology is confusing because we figure "memory" is remembered, but it is not; you need to use storage to actually keep anything. Also, although the amount of memory your computer is using at any given time can greatly affect its performance, you can't get a simple report from your operating system on how much is being used, like you can with your hard drive. This is because the way your computer uses memory is dynamic and complex.

See also: storage

read only

A state where certain data can be seen but not changed. If you open a document file that someone else is accessing over the network, your software may alert you that the file is in a "read only" mode on your computer, because two people on different computers shouldn't modify a document at the same time. This term can also apply to physical media, such as a standard CD.


See: regular expression


A company through which you can purchase ownership of a domain name. When you do this, the company inputs your name and contact information into the central registry of domain names for the Internet, along with the address of your domain's DNS servers so people can find your website and send you e-mails.

See also: domain name, DNS

regular expression

A method of comparing or matching text using a complex set of symbology to represent the desired pattern; regular expressions include many more methods of matching than simple wildcards. Ordinary computer users never see these, but system administrators use them in configuration files to trigger certain events based on text strings that might appear in log files, or even in a directory listing to find files based on the file name. Administrators might also use them to make adjustments to the content of text-based data files by finding and replacing text strings based on complex patterns. Software developers can use them in their programs to find information in text files, or to ensure text strings in the data being used by their program are in the appropriate format (such as for ensuring an e-mail address has an @ sign somewhere in the middle). Here is a simple example: In a program searching a file directory, the regular expression "Report_201[1-3]" would match files named "Report_2011", "Report_2012", and "Report_2013"" but not "Report_2003" or "Report_2014".

See also: wildcard

remote desktop

In the Microsoft realm, this refers to remotely logging on to a separate user session on a Windows computer from anyone else currently logged on; Microsoft also calls this Terminal Services in some contexts. In Apple (Mac) computing, "Remote Desktop" refers to VNC, a different system for remote access.

See also: VNC


A process by which a database is copied continuously to another server, so that the other server will take over providing user access to the database in case the primary server fails. Both servers in a replication pair hold a current copy of the database.

See also: backup

rich text

A data file containing readable text, along with standardized numeric codes that designate typeface, font, character size, and color of the text.

See also: text file

right click

The first mice used with computers had a single button. When a second button was added in the 1990s, the original button was placed on the left, and the new button was placed on the right, by convention. Since most computer software could not recognize more than one type of button back then, an ordinary mouse click—for selecting an icon or dragging a file, etc.—meant using the left button. As software was updated to recognize another button for special functions, using that second button came to be referred to as "right-clicking". On most computer systems, when you right-click on a program or file icon, a little menu of options appears related to that icon.


Remote Monitoring and Management. Software installed on workstations and servers that provides the ability for a remote or outsourced IT system manager to obtain alerts, perform updates and other configuration tasks, and observe overall system status and health on a dashboard. This term generally applies to third-party systems, as opposed to specific tools for remote management of a particular function, or a built-in solution by a given vendor for management of that vendor's systems.


Another term for malware, along with "virus", "Trojan Horse", and "worm". The term is usually applied to malware that installs in the inner rings of system security on a computer, making it extremely difficult to detect and remove.

See also: adware, spyware, virus


A networking device that sits between two or more computer networks, and conveys communications packets from one network to the appropriate target network based on the designated final destination of the packet. An example for a typical office is the router that connects the local area network (LAN) to the Internet.

See also: LAN, internet, switch, firewall


See: execute


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A computer operating environment that is securely separated from other software and data running on the same system through, and where access to shared system resources is monitored and tightly controlled, for the purpose of testing software in a safe manner.


A type of long-range wireless communications network which relies on equipment orbiting the Earth, and virtually no cabling on the ground. Commonly used with global positioning systems (GPS), and to receive television signals. Also used to provide Internet access in areas where land-based Internet access (DSL, cable, T1, phone lines) is not available. Also used to provide mobile phone service where there is no cellular network, using special satellite phones. If the satellite orbits at a high enough altitude, a signal sent from a device can be relayed right back down to a receiver on another continent. Some satellites orbit lower so that a device (such as a phone or handheld GPS navigator) can reach the satellite using only a small antenna rather than requiring a satellite dish.

See also: cellular, DSL, cable internet, T1


The ability of server hardware or software to be expanded to handle extra capacity (such as number of users, amount of storage, transactions per hour) in a cost-effective manner. For example, a pool of four servers that can be expanded to up to 16 servers, simply by adding 12 servers, would be considered scalable. But, if that system would have to be transitioned to completely different hardware and software (requiring upgrades and downtime) once the capacity of those 16 servers is maxed out, this platform would be considered less scalable than a different (and probably more expensive) platform of four servers that could be expanded to, say, 128 fully coordinated servers by simply adding them to the network. This word appeared often as a hot topic in the late 1990s when comparing the new Microsoft Windows NT Server product (with its limited flat network directory system) to Novell Netware and venerable UNIX systems for enterprise-level business applications, but then faded away upon the introduction of the highly-scalable hierarchical Active Directory for Microsoft's successor to Windows NT, called Windows 2000.

See also: elasticity


The structure of a database, not including the actual data. A database schema includes the names of tables and columns, data types to be stored (such as numeric data, alphabetic text, photographs, etc.), how the tables are related to each other, and how certain kinds of data inputs will trigger changes in other tables.

screened subnet

See: DMZ


A simple type of program, run directly from a text file. Usually implemented to perform simple functions, such as connecting your computer to a printer when you log on.

See also: program, text file


A flexible and robust hardware cabling system, signaling system, and communications protocol for attaching hard drives and tape drives to a computer or server, supporting internal and external connections. Early Apple Macintosh computers, UNIX workstations, and high-end IBM PC compatible servers used this in the 1980s, while it was available but not generally used for regular IBM PC compatible desktop computers. Due to its versatility, scanners and the original CD-ROM drives made in the early 1990s commonly connected via SCSI. Although many SCSI devices are still in use today, it has been largely replaced by SAS for new hard drives, and USB for peripherals like scanners.


In reference to computer files, this refers to retrieving a list of documents or database records that contain words or phrases you are searching for. In other words, files are retrieved based on the actual content, not just by name as when browsing. Similarly, in reference to the web, this refers to entering words into an input box to look for websites that have the words on its page or is otherwise related to the meaning of your words.

See also: browse

search engine

A website that provides links to websites (along with paid advertisements) that contain or relate to words or phrases you enter. The owners of search engines run programs on their computers constantly accessing and indexing the contents of as many websites as they can, with a goal of providing accurate and useful results in response to your search query. Common current search engines are industry leaders Google, Yahoo!, and MSN's Bing, as well as lesser-known older ones such as Ask, Lycos, and AltaVista (which simply returns results from Yahoo!).

See also: web portal, Google, Yahoo!, MSN

secure web gateway

A device or internet-based service that filters web access to prevent accessing unauthorized content and malware, protect against data disclosure, ensure regulatory and company policy compliance, and provide visibility on usage. To deploy this, a company's workstations and mobile devices are configured to route all web traffic through the secure web gateway, whether the workstation/device is on company premises or off-site.


1. Colloquial term for a very old but very common type of communications cable used for data terminals on mainframes and minicomputers, and to connect modems and mice to desktop computers. Also called asynchronous communications or RS-232.

2. Generally, any kind of communications system that sends data in a linear stream, such as peripherals that use USB, as opposed to sending it in chunks (called "parallel" transmission).

See also: USB


A computer on a network designed and configured for physically storing shared files, granting or denying permissions to those who try to view them, managing access to shared printers, running shared application programs and databases that users access over the network, and providing network-wide control services. Not designed for direct operation by ordinary users. Sometimes people refer to networking equipment in their office (such as a router, DSL modem, or even a cabling patch panel) as a "server", but this is incorrect.

See also: e-mail server, web server, workstation


A software process that handles functional tasks for a computer or server, but does not interact with a logged in user. A service can run regardless of whether someone is logged in to the computer. Services are often described as running "in the background". Examples are the components of a backup program that actually perform the backup; an e-mail server; a database server; file sharing; network services such as DNS and DHCP; virtualization hypervisor; endpoint protection software; firewalls; and a print spooler. For most services, other processes may act as a user interface to view the status of and control the service; when you shut down the user interface, the related service continues to run. For example, if you run a backup program and start a backup, you can close the backup program and log off the computer, and the backup will continue to execute.

See also: process, application, device driver, hypervisor

service pack

A set of software updates and patches all rolled into a single package.

See also: patch, update


1. An icon or button that gives access to a program, data file, or web page located elewhere.

2. A combination of keys you can press on your keyboard to immediately perform a certain function that would otherwise require clicking on several menu options or buttons.

sign in / sign on

See: log in / log on

sign out / sign off

See: log out / log off

single sign-on

A general term describing a system where a user signs in to a system once and then has access to related resources (such as shared folders, printers, and company intranet websites) without having to authenticate with each resource (such as by typing a password). One example is a system that saves passwords within a user's computer or cloud account data, and transparently sends the passwords every time the user attempts to access the resource. In this case, separate accounts and passwords still exist on each resource, and there is no coordination; the user's device manages single sign-on functionality. Another example is where servers in separate domains are configured to synchronize passwords, so a user can change a password on one system, and that system will update the password on the other; this approach is prone to problems due to synchronization problems or delays. Our last example is an IT system where an authenticating server provides a token once the user logs on, which the computer transparently sends to identify the user for authorized access to resources on the same company network (such as a Windows Server domain network, using an implementation of the Kerberos protocol). With this, there is only one account per user throughout the domain, handled by the authenticating server, and there are no separate passwords for the folders and printers within the domain. A single sign-on scheme reduces the number of passwords each user has to remember for various systems.

See also: domain, federation

smart card

A physical device that provides much greater authentication security than a simple password. Smart cards can be used for logging on to a computer, unlocking a door, or making payments. Each user's smart card holds a digital certificate only for that user, to prove the user's identity. The digital certificate itself is encrypted, requiring the user to enter a code (PIN) to unlock his digital certificate each time the smart card is used. This means that even if the card is lost or stolen, someone else cannot use the card without knowing the code; likewise, even if someone gets your code, he cannot do anything with it unless he also gets your card. Despite these advantages over passwords, smart cards are not widely used because a smart card system is expensive to implement and maintain.

See also: digital certificate

smart phone

This term, in just very recent years, meant a combination cellular phone and PDA. However, phones such as the iPhone and Android-based phones, as well as the latest BlackBerry phones, have become tiny little computers. When you have such a phone, you just call it by its name (iPhone, Droid, etc.). Everything else, which would have been called a "smart phone" in years past, is now just a "phone".


Acronym for Short Messaging Service, also simply called a "text message". This is the 160-character message you can send from your phone to another through the cellular network. Originally an odd and seemingly clunky feature of some cell phones during the late 1990s, it suddenly exploded in popularity in the early 2000s. Cellular systems are all linked to the Internet now, to allow transmission from old-fashioned e-mail and IM to SMS, and vice-versa.

See also: e-mail, instant messaging (IM)


Acronym for Simple Mail Transfer Protocol, which refers to the method of addressing and sending standard Internet e-mail, as opposed to the virtually obsolete other e-mail system protocols. When setting up e-mail client software on a computer, or adding an e-mail account on a mobile phone, you might see that the server designated for outgoing mail is referred to as the SMTP server.

See also: e-mail

social media

Messaging services available through websites and mobile apps that enable easy creation of personalized pages, private communication with designated friends, the ability to link up with new friends, and sharing of photos, videos, and links. Examples include MySpace (one of the early successful pioneers), and the hugely popular Facebook, Twitter, and the business-oriented LinkedIn.

See also: Facebook, Twitter, MySpace, LinkedIn


The program instructions that drive everything your computer and networking equipment does. The term is a derivation of "hardware", in that it is part of your equipment, but it is transient and invisible. It can be installed by copying the program instructions from a CD, or copied from another computer or from a web site. Software can be stored in RAM (when it is being executed), in silicon chips, and magnetically on your hard drive.

See also: hardware, RAM, hard drive


A term describing the implementation of information technology or communications hardware, software, and/or technical services to solve a problem, improve productivity, reduce costs, implement a user-facing application, utilize and manage data (enable access, move, duplicate, protect, recover, process, or analyze), or otherwise create new capabilities for a business operation based on information technology.

See also: point solution, integrated solution

source code

Program instructions in a human-readable syntax and format. Software developers write source code. Some languages can be run directly from the source code; these are called interpreted languages. For other languages, the source code must be compiled into binary executable program files to run.

See also: compile, binary, program


Unsolicited advertising received via e-mail; this can also refer to advertising placed in any kind of system, such as links to websites placed in the comments section of a news website.


Acronym for Stateful Packet Inspection. This is a feature of a firewall to allow incoming transmissions from computers outside the network only if a computer or device on the inside network has an active communications session that it initiated with that outside computer. The firewall records outbound communications by protected computers on the internal network into a database, called the state table. It then inspects each inbound packet and uses the state table to determine if it should be allowed. As an example, a web server cannot initiate contact with your computer out of the blue; your firewall will block the transmission. But, if your enter the web server's address into your browser, your computer will initiate communication with the web server, and your firewall will take note in the state table. When the server responds, the firewall will examine the incoming packet (containing the web page you wanted to see), determine that it is a valid response to your communication, and allow the packet to reach your computer.

See also: firewall


A type of application program that works with a grid of information in boxes called cells, with a primary purpose of performing mathematical and statistical computations, aggregations, and other functions with the data across rows and columns. The term also refers to the individual data files containing saved spreadsheet information.


A form of malware that, in general, tries to steal information from your computer, particularly passwords and financial information, and send it over the Internet to criminals.

See also: adware, malware


Acronym for Structured Query Language. This is a method by which a computer program accesses a shared database on a database server, which is referred to as the SQL server.

See also: database


Acronym for Solid State Drive. This refers to a hard drive with no moving parts, using solid state technology, which can offer better performance in many applications than a conventional hard drive using spinning magnetic platters.

See also: hard drive, magnetic


Acronym for Secure Shell, a protocol for logging in to the command line interface of a remote computer or network device in a secure fashion, using digital certificates to confirm the identity of the server, and setting up encrypted communications to prevent eavesdropping. This protocol is most commonly used to log in to network devices such as routers and switches to change the configuration or check the log files. It is also used to log in to UNIX-based computers over the Internet to manage the programs running on it (such as restarting a crashed web server) or change configuration options or review logs. The protocol was invented by a university student in Helsinki.

See also: Tatu Ylönen, command-line interface


Acronym for Secure Sockets Layer, a protocol for accessing standard server services (such as web pages or e-mail) in a secure fashion, using digital certificates to confirm the identity of the server, and setting up encrypted communications to prevent eavesdropping. This protocol is in use when you visit a website using the https:// designator, and often for transport of e-mail. The latest versions of SSL are called TLS, an acronym for Transport Layer Security.


See: single sign-on

static IP

This is an IP address assigned by your Internet access provider that is fixed, not subject to change. Although this will cost more per month than a dynamic IP address, it is useful if you run your own web or e-mail servers.

See also: dynamic IP


An upgrade from the current edition of application or operating system software to an edition with greater functionality and features (such as the Home edition to Professional), without upgrading the version (as from version 3 to 4). The price is usually a little bit more than the difference between the two editions.

See also: upgrade


Refers to components of a computer that retain information even when the computer is shut down. The primary device for this is the hard drive, but backup tapes, recordable CDs and DVDs, thumb drives, and external (USB) hard drives are also forms of computer storage.


This term is mostly used by software developers, but you might see it in the general IT realm as well. It relates to processing of text. Whereas a "character" refers to a single letter, digit, punctuation mark, or a space between words, a "string" is a sequence of such characters, forming a phrase or sentence.


A computer designed for cutting-edge computational ability for solving complex problems related to mathematics, engineering, or even the natural sciences.

See also: mainframe

surge protector

A device (usually in the form of a strip of electrical outlets) that provides protection against sudden increases of electricity being pushed to your computer, monitor, or printer, to prevent catastrophic damage in the case of a major power surge, as well as the gradual damage caused by repeated minor surges. A surge protector alone does not provide any electricity in case of a power outage, no matter how brief.

See also: power strip, UPS


See: secure web gateway


A network device that connects multiple computers, and manages the communications traffic, within a local area network.

See also: router, LAN


Short for synchronization. This is a method by which devices that are not always directly connected to each other can maintain the same set of information. Many people used this for Palm devices, the BlackBerry, and other smart phones like the Treo for many years. You could update your contacts and calendar on either your computer or the device, then plug the device into your computer, and both would update each other with the changes you made. As another example, a laptop user might have a copy of shared files from the company server stored on his laptop, so that he can open and edit them when outside the office; whenever he comes in to the office and connects to the network, the laptop uploads new and changed files to the server, and retrieves changes other users made to other files since the last time he synchronized. Using any system that performs automatic sync must be carefully planned and managed, especially with large sets of information or poorly-written software, to avoid duplicated, deleted or corrupt data.

See also: PDA

system architecture

The overall structure of an information technology system, viewed from a broad level, and considering business requirements for performance, capacity, availability, security, and fault tolerance. The architecture establishes configuration standards for the components within.

See also: configuration


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Technology dating back to the 1960s that allows digital communications (such as connections between networks in different cities), as well as a digital phone line trunk, and connection to the Internet, all over ordinary copper telephone wires, even over very long distances (with repeaters). Transmission speed is about 1.5 megabits per second. Until recently, the core routing technology of the Internet ran over T1, gradually being replaced with fiber.

See also: DSL, cable internet, fiber


A portable computer about the size of a very thin notebook, but generally with touch screen capabilities instead of a keyboard; usually much more limited in capabilities and power in the interest of being small and light. While these have been around for many years, the popularity of the Apple iPad created new interest in tablets and spurred other manufacturers to come out with new models to compete.

See also: laptop, notebook, ultrabook, iPad


Magnetic storage technology used since the earliest days of computers. Data is stored on long, narrow strips of plastic coated with magnetic material and spooled on reels inside a plastic cartridge. Compared to current widely available storage technologies, data access on tape is very slow, because it requires a tape drive that forwards and rewinds the tape to find or record data to the proper part of the tape. Because of this, tape is used today only for backup and offline storage.


The data transport system that underlies everything you do over the Internet, and when communicating with other computers on your office or home network. Originally invented by the U.S. Department of Defense in the 1960s for the purpose of ensuring a nationwide network of computers could continue to communicate even if large portions of it were destroyed by the Soviets. It is the subject of much study and experimentation due to its breadth of related subjects and technical complexity.

See also: IP address


A user of a conventional host server or cloud system where applications and services are shared, but user data is kept separate. The tenant can manage resources and application configuration that applies to the tenant through an administrative console, including adding resources (such as storage or processing power) up to the limits of the tenant's account. The administrator of the host server or cloud system can see resources allocated to all tenants, adjust resource allocation, and add physical resources to the system to expand a tenant's allocation and/or add new tenants. A tenant can be a customer of a public service provider, or one of multiple departments that share a company's private servers. Tenancy applies to server-based applications or services that are administered on behalf of users of that application or service. For example, a mail server might host multiple companies with separate sets of mailboxes on different e-mail domains; each company is a tenant. Or, a virtual machine platform can host separate virtual networks and sets of virtual machines used by different tenants, which have no connection to each other. The owners of separate unrelated web sites on one web server are tenants. A user with an e-mail account on an e-mail server, even with allocated storage space, is not considered a tenant in relation to other users with addresses in the same domain.

See also: hosted service, cloud


About a trillion bytes, used for measuring file size or storage capacity.

See also: byte, kilobyte, megabyte, gigabyte

text file

A data file stored on your computer that contains nothing but ASCII codes for letters, numerals, punctuation, tabs, and line breaks. There is no information about fonts, typeface, character size, colors, etc. Text files are more often used by administrators than ordinary users, to save computer configuration information to be read directly by the computer.

See also: rich text

text message

See: SMS

thumb drive

A hardware device, about the size of your thumb, that you can plug into a computer's USB port, for transferring files to and from your computer. Thumb drives now come in many fancy shapes and colors, but also are able to store quite a bit of data, presenting a significant security risk in controlled networks.


Acronym for top-level domain. Also called a superdomain, this is the part of an Internet domain name after the "dot", in the Internet DNS system. The original TLDs were .com, .org, .net, .gov, .mil, and .edu, indicating a commercial enterprise, non-profit organization, network operations center, U.S. government network, U.S. military network, and U.S. university, respectively. Different TLDs are managed by different agencies, with different levels of restrictions. For example, despite the original intent of categorization, today anyone can register any domain under .com, .org, or .net regardless if your company fits the intended use (or even if you're an individual). But, you can't register a .mil address. There is a two-letter TLD for over 250 countries (including .us), managed by the respective country. Starting in 2001, several more were created (such as .info and .biz) every few years, until 2014 where we saw a flood of hundreds of new ones that are now getting quite weird (such as .beer, .fail, .toys, and .moe).

See also: domain name, DNS


See: SSL


A set of buttons or little text boxes (for you to enter information, such as a search request), that is added to your web browser (or other kinds of applications), to provide easy access to a program on your computer, or even to easily access services on a web site that you don't currently have open in your web browser. An example of this might be the Google Toolbar, which allows you to run searches on Google without having to open the Google website first, and which will monitor other services of Google you might use even as you browse other web sites.


A computer that stands vertically tall, and is often placed under the desk, or on top of the desk alongside the monitor, as opposed to a desktop form-factor computer that lies flat.

See also: desktop

transaction log

In some database systems, any changes (inserting, editing, or deleting information) are recorded to a set of files called the transaction log before being applied to the database file itself. While this improves speed and greatly reduces the chances of data loss in case of an unexpected shutdown other error, an experienced system administrator often must manually intervene in order to bring a transactional database back into operation following a crash. A database that does not use transaction logs generally comes back online by itself, but recent changes might be lost.

See also: database, log file, fault tolerance

Trojan Horse

Another term for malware, along with "virus", "rootkit", and "worm". The term is usually applied to malware that is installed deliberately (but unknowingly) by a user, because it came along with what the user thought was a legitimate software package. Named, obviously, after the ancient story of the Greek ruse in the Trojan War.

See also: adware, spyware, virus


The process of accounting for licenses that have been used during the prior term when renewing subscription-based software for a new term. This might involve paying pro rata for excess licenses used in the prior term, and then renewing for the coming term at the higher level. Or, if users had been reduced, reducing the licenses for the coming term.

two-factor authentication

See: multi-factor authentication


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A relatively new term, from just the past year or so, for a very light, thin, Microsoft Windows based laptop computer meant to satisfy those who like tablet-sized computers with a touch-screen, but provide a keyboard, better computing power than a tablet, and a standard operating system such as Microsoft Windows as opposed to something like Android or Apple iOS. These typically come without a DVD drive or network port.

See also: laptop, notebook, tablet


Acronym for Universal Naming Convention, which is a technical method of distinctly naming a folder shared by another computer on a local area network (LAN). It is formatted as \\server-name\folder-name, which can be followed by more subfolder names. For example, if a server named "FINANCE" had a folder shared named "REPORTS", the UNC to that folder would be \\FINANCE\REPORTS. In some systems, a regular slash / is used instead of a backslash \.

See also: backslash


A successor to ASCII, developed in the late 1980s and now in wide use by most applications. By using multiple-byte characters, it allows for thousands of different characters from many foreign languages, all in one standard table.

See also: ASCII, byte

unified threat manager (UTM)

A marketing term describing firewalls that appeared around 2004, targeted to the small/medium business market, that perform basic intrusion prevention in addition to the conventional function of blocking or allowing traffic based on address and packet type, and further examine the content of all communications so as to detect and block junk mail (anti-spam) and viruses (anti-virus), as well as perform website filtering (blocking access to disallowed websites based on address and/or content). Having all these functions available in one device was generally attractive to a business with limited IT support and without any of these various protection mechanisms already in place, and for which the slowdown by all these checks is not a problem due to light Internet access. But, some UTM manufacturers have, in recent years, added enterprise-grade features such as better performance, dynamic routing, clustering, scalability, and directory integration, blurring the distinction between UTM and NGFW.

See also: firewall, next-generation firewall (NGFW), intrusion prevention system (IPS)

unstructured data

Electronically stored information that is stored outside of a database schema. This includes virtually all user-created information, most significantly the files and folders stored on a shared drive, or in a web-based file storage system. It includes word processing documents, spreadsheets, photos, video files, desktop publishing documents.

See also: database, schema


A small program that installs new components of a software program, either to fix bugs or provide minor new features. These are generally provided free by software manufacturers.

See also: patch, upgrade


A new version of a particular application program or operating system, which requires completely replacing the existing version. For paid commercial software, software publishers usually offer the latest version of software at a discounted "upgrade price" to those who already own an earlier version, or for free to those who pay a monthly subscription fee to use the software. Regardless, the software upgrade package will always contain all the program components and functionality as the higher-priced version you would have to buy if you didn't have the previous version already (often colloquailly called the "full" version).

See also: patch, update


To transfer a file, such as a program, document, photo, or video, from your computer to another computer or web site. Or, more generally, outbound communication from your computer or network to the Internet.

See also: download


Acronym for uninterruptible power supply. Also known as a battery backup, this is a device that provides electricity in the event of a short-term power outage, by using a battery inside the device, which keeps itself charged so long as the power is on. The UPS immediately provides power to your computer, with no break in continuity, when it detects that electricity has stopped coming from the wall outlet.

See also: surge protector


See: URL


Acronym for Uniform Resource Locator, sometimes referred to as URI (Uniform Resource Identifier), which is the format you use to access services through your web browser, either by manually typing the URL, or clicking on it in a hyperlink or in an e-mail. Most often, this simply refers to a web page address that includes a particular page within a web site. That is, as opposed to just the domain name of the web server, a full URL/URI includes the protocol designator (which is HTTP for web pages) and the name of the page. For example, whereas the domain name for the entire J.D. Fox Micro web site is, the URL for this Glossary is

If a different protocol is specified (such as rtp: or ftp:), your web browser may launch another program to retrieve the information at the specified address and handle that for you.

See also: web site, web server


Acronym for Universal Serial Bus, a type of computer port developed in the 1990s for connecting peripheral devices such as keyboards, mice, printers, scanners, cameras, and external hard drives. Before the introduction of USB, all of the previously-mentioned devices connected to different kinds of ports.

utility computing

See: cloud


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A broad and flexible term describing any situation where a hardware device, software application, or other function is emulated, including multiple separate instances. For example, a virtual printer might be represented as an icon in your Printers folder on your computer as if it were a real printer; this allows you to print from any application you have, but send the printed image into a PDF file or dial a fax machine, instead of physically printing it on a page. For another example, Microsoft uses the term SMTP virtual servers to describe their edition of the industry standard SMTP application when running on Windows Server. Normally, SMTP server software has a single configuration per server. On Windows Server, each SMTP virtual server has a separate configuration, mail queues, and logging. The Apache web server has also used the same term in the same manner. As another example, virtual applications are user programs (such as a word processor) installed on a server and accessed over the network, instead of being installed on each workstation in the organization. These run in a window on your workstation as if they were installed on that workstation. While performance will be slower, this makes it much easier to upgrade the application for all users or standardize its configuration. As another example, a virtual PBX is a phone system hosted transparently on the Internet, where inbound trunk lines go to the PBX provider's site, and your extensions connect via the Internet, requiring no physical PBX hardware. Finally, an entire computer, or set of computers and their local network, may be virtualized (see virtual machine, below).

See also: virtual machine

virtual desktop

A computer with a full desktop operating system and applications that runs as a virtual machine on a server, and is accessed by users over the network from a workstation or tablet. This allows a user to move around and have all the same software, network connections, and files available no matter what computer or tablet he uses to log in.

See also: virtual machine

virtual machine

A software application running on a computer that completely emulates an entirely separate computer, with its own installed operating system and applications. This enables the versatility of running single-purpose servers to avoid application software conflicts, without requiring a separate physical server for each. It also enhances fault tolerance, as a virtual machine can be copied, intact, to another physical server should its current physical server suffer a component failure. Each virtual machine must share processor time, RAM, and access to the network with other virtual machines running on the same host computer. Apart from servers, a user may choose to run a virtual machine on his computer; typically, this involves running a Windows virtual machine on a Mac, so that someone with a Mac can use applications that only run under Windows.

See also: virtual desktop


1. The process of emulating computer servers and workstations, computer components (such as hard drives or network adapters), physical networks (such as an Ethernet segment), or network services (firewalls, routers) in software. This usually involves consolidating multiple such physical components to operate simultaneously on one or a relatively small number of physical computers.

2. The process of transitioning a set of servers from running on separate physical machines to running as virtual machines.

See also: virtual machine


Another term for malware, along with "Trojan Horse", "rootkit", and "worm". The term can fairly be applied to most any malware. However, some IT professionals, IT trainers, and authors try to parse the technical differences between various types of malware, and object to using this term so generally. But in reality, there is no formal standard definition for these terms, so different sources might provide different definitions. Besides, malware is too complex to fall neatly into categories, and the naming of any given piece of malware is not helpful in preventing, detecting, and removing it.

See also: adware, spyware


Acronym for Virtual Network Computing. A technology by which a user may see the screen, and control the mouse and keyboard, of one computer from another. Referred to by Apple as Remote Desktop. Useful for tutoring, training, and diagnosing issues for a particular user.

See also: remote desktop


Acronym for Voice over Internet Protocol. A technology by which a phone can connect to a regular computer network instead of traditional copper wires, and convey your voice through computer data packets. When used to call from your office to another VoIP phone over the Internet, this allows for cost savings by avoiding long-distance and even international tolls from traditional phone service providers. Even if only used internally in your office (with a bridge to the conventional public phone system), this enables centralized phone and call control features only previously available with very expensive phone systems, and some features that are otherwise impossible. For example, when your phone and computer are on the same data network, your CRM application can automatically open the file for a customer when the phone rings with his caller ID. Drawbacks of VoIP include potential loss in quality of the audio and reliability (especially when talking over the public Internet), and greater security considerations due to its connection with your information technology system.

See also: CRM


In data storage, a volume is an independent, self-contained, logically contiguous file storage area on a hard drive, CD, DVD, thumb drive, or even floppy disk. For most media, the entire disk or device is one volume. Hard drives can be partitioned, though, and each partition on a hard drive typically contains one volume. But, multiple hard drives and partitions can be combined into a single volume for greater capacity, fault-tolerance, and/or performance (depending on the configuration). On Microsoft Windows computers, each volume is assigned a drive letter; in Mac OS each volume can appear on the desktop; in UNIX-type operating systems, a volume must be mounted into the filesystem hierarchy.

See also: hard drive, partition


Acronym for virtual private network. This involves connecting to a network (not just to one computer) from outside that network, through the Internet. Once you are connected, you can access data and services on that remote network as if you were actually in the building and physically plugged into the network. This is a common technology for laptop users to access shared files, databases, and applications in their office while on the road, or for telecommuting users to work from home. The term can also refer to two geographically separated networks that operate as one congruent network due to a VPN link between the two networks; this will be managed by your IT service provider.


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Acronym for wide area network. A system of connecting computers across distances beyond the capabilities of LAN technologies (such as Ethernet), using anything from dedicated T1 links, ISDN, dial-up modems over the standard telephone network, fiber, or satellite.

See also: LAN, network, T1, ISDN, dial-up, modem, fiber, satellite

web browser

A program that runs on a personal computer, laptop, or handheld device which you must use to view websites, move back and forth through the set of pages you have recently visited, and save the address of pages you like to your "Favorites" or "Bookmarks" list. Common browsers are Microsoft Internet Explorer, Mozilla Firefox, Google Chrome, and Apple Safari. Older browsers no longer in use include the America Online client software and Netscape Navigator. Whenever you open your web browser, it connects to a site designated as your "home page" and displays it. From there, you can enter the address of another website in the browser's address bar, click on something in your Favorites or Bookmarks, or enter a search term into a search engine, if you want to go to another site.

See also: home page

web host

A technology services provider that stores your web site on their web server for a monthly fee, and provides continuous availability to this web server over the Internet for visitors to access your web site, browse its pages, and utilize any services you provide through the web site, including making purchases.

web link

This is a word, image, or button that appears highlighted or underlined to indicate that there is an unseen tag containing the address of a web page. Clicking on a web link will open the target web page in your web browser. Originally only found in web pages, web links can appear anywhere now on your computer, such as inside a word processing document or e-mail message.

web mail

A system of accessing e-mail without having to use conventional e-mail software programs. You can read and send messages by logging in to the web site run by your e-mail service provider. An advantage is that e-mail is accessible from any computer; a disadvantage is that e-mail is more cumbersome to handle through a web browser.

web page

A single document from a web site as displayed in a visitor's web browser.

See also: web site

web portal

A web site that is intended to provide vast, up-to-date interesting and customizable information such as news, sports scores, weather, games, easy access to your web mail, and links to other web sites of interest, as well as the ability to search the rest of the web for anything else. The web portal industry is highly competitive due to the advertising revenue it can bring. Many people find themselves on a given web portal not by choice, but because their computer manufacturer or the publisher of any kind of Internet related software they might buy sets their computer to go to a given web portal when the user opens his web browser. Examples are MSN, Yahoo!, and America Online.

See also: MSN, America Online, Yahoo!

web server

A computer designed and configured to store the contents of a web site, and respond to requests from visitors from all over the Internet to access web pages or other web-based applications and services.

See also: web host

web site

A collection of web pages and related interactive services hosted under a given domain name.

See also: web page


The current standard, which defines signalling methods and security, for connecting to a network wirelessly within a limited range, through which you can then access data and services on that network, or use its connection to access the Internet. If you have an old laptop with wireless capabilities that does not conform to the Wi-Fi standard, you may not be able to connect to a modern wireless network.


A symbol used to represent unspecified characters. Most commonly, the star symbol (*) means any number of characters, and a question mark (?) means any single character. For example, if you had files named "report.2013.Finance", "report.2014.Finance", and "report.2014.Acquisitions", then a command to delete "report.*" would delete all of them, while a command to delete "report.201?.Finance" would delete just the first two. If you are getting into using a UNIX shell and writing scripts, it is important to understand whether * or ? represent wildcards as described above or are being used in a regular expression, because these symbols have different meanings in regular expressions than when being used as wildcards. Whether these symbols are wildcards or are part of a regular expressions depends on the context in which they are being used.

See also: regular expression


A broad term referring to all kinds of communications using electromagnetic waves. It refers to secured, local connections to your office network or to the Internet at a public hotspot (via the Wi-Fi protocol), but it also refers to cellular communications through your cell phone carrier's network of cell phone towers, as well as the simple signals from a wireless keyboard and mouse to your computer.

See also: hotspot, wireless router, Wi-Fi

wireless router

When you have a connection from your home or office to the Internet via DSL or cable, a wireless router enables you to share that Internet connection with a laptop or tablet via Wi-Fi.

See also: Wi-Fi


A computer designed for operation by an ordinary user for running applications; generally a synonym for desktop. In the 1990s, this term meant a very high-powered desktop computer such as those made by Sun or SGI, but is no longer used in that context.

See also: desktop, server

World Wide Web

Also called "the web" for short, this term refers to the collection of servers on the Internet that provide formatted graphical pages of information which include clickable links to other pages on the same site or to any other site. The limitless many-to-many links between sites is what comprises the "web". Web sites are relatively new to the Internet, having been invented in 1991. Prior to that, the Internet was used for many other functions, such as a bulletin board system called Usenet (what we would now call a forum), libraries of program or data files available for download, remote operation of all kinds of applications on powerful campus computers, e-mail, and a chat system called IRC. Since web sites are flexible, accessible, intuitive, and highly visual, all of these functions can now be accessed by visiting a web site first, which is why "the web" and "the Internet" have become synonymous.

See also: Internet, Tim Berners-Lee, HTML, web browser


Another term for malware, along with "virus", "Trojan Horse", and "rootkit". The term is usually applied to malware that spreads by itself from computer to computer over a local area network.

See also: adware, spyware, virus


See: World Wide Web


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Any kind of computer or network infiltration that is unknown to anti-virus or intrusion prevention software; that is, the infiltration method or virus file is not listed in the threat/virus definition database of the security software. Zero-day attacks will not be stopped, except by security software that uses sophisticated methods to detect and prevent unknown viruses or exploits.

Zip file

A standard method for combining and compressing files, without any loss of data. Modern computers natively support creating and opening these files; in the past, you had to use separate application programs such as PKZIP or WinZip. These applications are still available, with extra features such as encryption.

See also: compression

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