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Glossary of Computer and Internet Terms
A glossary of computer and Internet terms with definitions that are easy to understand.
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There are 596 entries in the glossary.
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Term Definition

Text Editor

Text Editor is basically a word processing program that allows you to edit the text. HTML code can also be written using a text editor.


TFT (Thin Film Transistor) are used in LCD screens and work by having a transistor for every pixel that makes up the screen. As they light up the image is brighter and sharper as the transistors can turn on and off faster. These displays are known as active - matrix displays.

Thick Client

A Thick Client is a functional computer connected to a network. They are mainly used in businesses when connection to a server makes them a client as the files accessed are not stored on the computers hard drive. When disconnected from the network, the usual name for a thick client is a workstation.

Thin Client

Thin Clients are computers that are stripped down and do not contain a hard drive or features such as extra I/O ports. Thin clients do not have software installed preferring to access data and run program from a server instead. Thin clients must, however be connected to a network. Many businesses run thin clients in order to do one thing at the same time as it is cost effective.


A Thread is a process in a computer program that is part of a sequence and runs as soon as the program tells it to. Many computers can operate multi threading which means several threads can be run at once, and some threads take precedence over others. Thread can also be used to describe postings on forums or chat rooms.


A Thyristor is a semiconductor that has four layers and is primarily needed to handle a large amount of power. It can be on or off but it can also be used to regulate power using a phase angle control. This works very much like a dimmer switch by adjusting the angle input to thus control the output. As a Thyristor can be turned off by adjusting the direction of the current they are not very useful for applications that use low power. Similarly as they can only conduct power in the one direction they are of no use when a current has to be conducted to and from certain devices.


TIFF (Tagged Image File Format) is a file format for graphics that was developed in the 1980s in order to standardise graphics across many computer platforms. It is capable of handling many different colour depths.


Tiger is the name for the Mac OS X 10.4 (2005). Apple have stated that the Tiger has around 200 improvements more than the 10.3.


TLD (Top Level Domain) is a term that is used for the very last part of an Internet domain's name. For example for a domain name that ends in .org the .org part of the domain name will be the TLD.


The term Token has three meanings, the first one is used with reference to networking. It means bits that are circulating on a token ring network. Only one computer can send data at any one time and it is the computer that has the token. The second meaning is to do with programming and a token is a single element, such as a punctuation mark, operator or reserved word which is part of programming language. The third meaning is to do with security systems and is an ID card that is needed to log into certain networks. When the user of the card enters a password the card then shows the current ID code which the user will need to log in. As this password will change around every 5 minutes it enhances the networks security.


Toolbar is the row or block of icons on a screen that will activate functions when clicked, it is a type of graphical interface.


Toslink is a Toshiba developed digital audio connection. Fiber optic cables are used to transmit audio signals and one cable can be used to carry different types of audio signal such as surround sound, stereo or mono. As fiber optics are used there is no electrical interference and this improves the sound quality. Toslink is usually found in high quality home cinemas and professional equipment.


Traffic is the term used to describe the number of visitors that visit a web site and which pages they access. This traffic is closely monitored in order for the web site developers to determine which sites and pages are popular.


Trinitron is a form of Cathode Ray Tube technology, and it is possibly the best available. Trinitron sets itself apart from other tubes by using an aperture grille (wires which are spread vertically across the screen) rather than a shadow mask (a metal plate that has holes in it which lets the image show through) when it is creating images on the screen. As a result the image has much less distortion.

Trojan Horse

Like in the myth Trojan Horses are certainly not what they appear to be. They can come disguised in the form of software than once installed and run they can be potentially deadly to your computer.


TTL (Time to Live) is used to describe when a ping is sent to a computer which is then sent to a different computer, like a server. TTL is equal to the number of hops the ping travels to before it returns an attempt failed message.


Tutorials are computer based learning packages. They can be done at the learners own pace and have varying degrees of difficulty. Some tutorials are simply a walk through of a software package whilst others can be aimed at developing a particular skill such as typing or Website design.


The actual meaning of TWAIN is somewhat unclear but it allows developers to make digital scanner and camera drives against a standard. Almost all scanners today adhere to this TWAIN standard.


When you Tweak something you are modifying it. Altering settings on a computers motherboard is an example of tweaking hardware , adding plug-ins and removing system limitations are examples of software tweaking. Tweaking a computer is like tuning your car and will improve it's performance.


Typeface's are a set of characters all in one design and they include letters, symbols and numbers.


U is a unit of measurement that is typically used to measure rack-mounted equipment such as hard drives, switchers and routers. One U measures 1.75 inches, so a piece of equipment that is 24 inches long (the length of a normal rack) but 1U high is thought to take up a unit of rack space.


UDP (User Datagram Protocol) is a section of the TCP/IT suite of data transference protocols. It is normally used for streaming media as it doesn't acknowledge when the data has reached it's destination.

Ultra DMA

Ultra DMA is a method of transferring data to and from a computer's memory and hard disk and it's highest burst rate is 33.3 MBps which is double that of the original DMA. Not only does Ultra DMA make your computer run a lot more efficiently it also features a utility called Cyclical Redundancy Checking that enables data integrity protection.


UML (Unified Modeling Language) is a form of programming language that was developed to assist object-oriented software developments. Programmers tend to make objects that consist of uniform sets of data that are located in a program in order to organise their program codes more efficiently.


UNC (Universal Naming Convention) is a term for a filename format that highlights the locations of folders, files and resources on a LAN. It is also used to locate peripherals used by several computers on the same network.

Unique Visitors

A Unique Visitor is a real person who has accessed a Web site and the Web server records the IP address so regardless of how many pages that person accesses they will still only be counted as one.


Unix is an operating system that was created by Bell Labs in the 60s and it gained support from high-level programmers in the 70s. The first internet services originally were hosted by Unix machines it became a lot more popular in the 90s. There are various different versions of it and all run on many different operating systems so it becomes somewhat confusing, however the majority of people never need to use Unix.


Upload is the term used to describe the act of sending information from one computer to another.


URL or Unique Resource Locator is basically a Web address.


USB or Unique Serial Bus is a way of connecting devices to a computer and USB ports are the most popular way of doing this.

User Agent

A User Agent is a client application that is used with a specific network protocol. The term is often used with reference to the ones that enter the World Wide Web such as spiders and web browsers. They can also be used to help people with disabilities use their computers better.


A Username is the name that a person uses to identify themselves on a computer system. One computer can have many different users but if they all have different usernames (and passwords) then they can access their own accounts on that computer.


Utilities are software programs designed to increase a computers functionality and such programs are anti virus, back up, disk repair etc. In short anything that helps your computer to run more efficiently is classed as a utility.


VCI (Virtual Channel Identifier) is used with a VPI to show where an ATM needs to move over a network. As this is a data transfer method the VCI that is contained in every ATM cell determines the fixed channel that the packet has to be sent. As these virtual channels are so strictly defined it prevents interference with other data on the network.


Vectors are definitions of the paths that are used to create EPS files and Adobe Illustrator documents. The term is also used in computer science and is a one dimensional array.

Vector Graphic

Vector Graphics are images that are made up of paths (unlike JPEGs, BMPs and GIFs which are made up of pixels) and these paths can go in any direction and make up any shape but they all have a start and ending points. As vector graphics are made up of these paths they can be scaled up or down and not lose any quality.


Veronica (Very Easy rodent-Oriented Netwide Index to Computerised Archives) allows a user to search all of the gopher servers in the world using keywords and then it will list all of those gopher menu's that have the keywords in the. Newer versions will search newsgroups and Web pages although unlike a search engine it will still only look for the keywords in the title of a document, not in the text.


VFAT (Virtual File Allocation Table) is used in operating systems newer than Windows 95 and is responsible for organising and accessing files on a computers hard drive. VFAT Files can also have names that are up to 225 characters long.


VGA (Video Graphics Array) is IBM developed and is used in most computers today and is a standard display or monitor interface. The most recent version allows resolutions which are larger than 640?80.

Viral Marketing

Viral Marketing is a method used to manipulate social networks that already exist in order to further awareness of a brand or product.

Virtual Domain

A Virtual Domain is a way of redirecting a URL if it exists in type but not on a server. There are services that will do this and it is normally favoured by sites that have a very long and complicated URL - the shortened URL will be typed but the traffic is redirected to your longer URL.

Virtual Hosting

Virtual hosting is the term used to describe the way that Web servers can host multiple domain names on one computer and IP address.

Virtual Memory

Virtual Memory is a way of increasing your computers memory without altering the amount of RAM that is installed. Most computers will only support a certain amount of RAM and sometimes needs more and this is where virtual memory comes in. Your computer will use up places that are in it's memory where additional data can be stored. The hard disk is normally used for this but it does slow down the computer. In order for your computer to run better you should try to have the maximum amount of RAM allowed for the machine.

Virtual Reality

Virtual Reality is a way of putting yourself via computer simulations (using a headset and specialised glasses) into a virtual world. Virtual Reality is mostly used to entertain but it can be helpful in training people in the medical and military fields.


A computer virus is a malevolent program or sometimes a script that once inside your computer will do a lit of damage. Virus's can remove or change files, use up your computers memory and generally make using your computer a nightmare. In order to prevent attack by a virus never open suspicious emails and make sure you have Anti-virus software on your computer and remember to scan your computer regularly.


VLB (VESA Local Bus) is a term used to describe a hardware interface that is located on a computer's motherboard and is attached to an expansion slot and adds extra graphics to your computer. It is little used now however.


VoIP (Voice Over Internet Protocol) is a telephone line that is used over the Internet. The information is digitally sent and using VoIP is free so eliminates long distance phone call bills. In order to use VoIP you need (as well as a computer and Internet access) VoIp software which can be downloaded for free and a microphone and speakers, although you can buy VoIP telephones and headsets.


Volume in computer terms means devices such as DVD drives, hard drives and other devices such as USB keychain drives. As long as the computer recognises the file system within them it can read them. On Mac computers any volumes that are interfaced with the computer will be on the desktop.


VPI (Virtual Path Identifier) is a header that has 8-bits that is inside each ATM cell that tells the ATM where to route the packet data to. Many ISPs use this method to transfer data between client computers.


VPN (Virtual Private Network) is used mainly by large companies as it encrypts all the data being transferred via the Internet so that it cannot be seen. Hence the term "Virtual Private Network" it is similar to having the Intranet via the Internet.


VRAM (Video Access Random Memory) is used to keep the images that your computer shows on the screen. When an image is meant to be displayed the processor will read it then write it to VRAM. This is then decoded and displayed on the screen. Images can be read and written by VRAM at the same time to prevent images from flickering. VRAM has several types, the most popular being Synchronous Graphics RAM which is synchronised with a clock, this means it handles data more efficiently and in one operation. Rambus Dynamic RAM is the best kind for video editing and the choice of many professionals.


VRML (Virtual Reality Modeling Language) is method of creating virtual 3D tours of places and buildings, these interactive navigation tours can also be used to allow people to see inside vehicles from their Web browser.


WAIS (Wide Are Information Server) is a term used to describe a vast index of information that can be searched through and across various networks, the Internet being one of them. Searches can be narrowed down and researched to improve the relevance. The new version of WAIS are search engines.


WAN (Wide Area Network) is a much larger version of a LAN (Local Area Network) and they can be spread across thousands of miles via telephone lines and satellite link ups.


Waveforms are graphical versions of audio recordings that move up and down x and y axis's as the amplitude and time pass.

Web Host

A Web Host is needed if you have a Web site and it stores all the data on your Web site and ensures that it is available to those who use the Internet. The name of the Web site is connected to an IP address so when an IP address is found (through typing the domain name into their browser) the Web site is then loaded directly from the Web Host.

Web Hosting

Web Hosting is the term used to describe a service that offers provision for storing images, documents, video or other content online for Internet users. Web hosts are the companies that offer space on their server for their clients.

Web Page

Web pages are documents written in HTML and are either static (never change) or dynamic (are updated regularly) and are accessed through a browser. They are usally written in Perl, ASP or other scripts.

Web Ring

A Web Ring is a collection of linked Web sites that can be accessed in a loop from one another. Web rings can be used by going backwards or forwards through all the Web sites using a button, or you can choose which Web site to go to from a list.

Web Server

A Web Server is a computer that can store HTML documents (which can be extracted through a Web browser) that is connected to the Internet.


A Webmaster is the person who is responsible for a Website, they make sure that all links are working, check the content and perform other housekeeping tasks on a Website.


In very simple terms a Website is a compilation of web pages, and there is no minimum or maximum number of pages that can create a Website.


WEP (Wired Equivalent Privacy) is part of the security system for Wi-Fi networks. As Wi-Fi networks use radio waves they can easily be 'listened in' to so WEP encrypts the data being transferred. Network passwords are used to access the Wi-Fi networks.

White Paper

A Whitepaper in computer terms is different to those in political terms. It is the term used to describe anything published that explains a particular technology.


Whois is used to ask a database who owns a domain name, IP network or other ownership queries.


Wi-Fi (Wireless Fidelity) is a term used to describe wireless network devices that are founded on the Wireless Alliances 802.11 standards. This means that any Wi-Fi device can be used with any Wi-Fi certified access point.


Widgets are small programs that are used on the Yahoo! Widget Engine. They are also used on the Mac OS X Dashboard. As Dashboard and Yahoo are not compatible with one another separate similar widgets must be created for every widget engine.


Wiki's are websites that are created by people adding to them from their own browser. Wiki software runs on a Web browser to enable this. Possibly the most well known and largest of all Wiki Websites is the Wikipedia which is an online encyclopedia that is free.


Win32 is used in creating 32 bit applications and is an API (Application Programming Interface) any version of Windows after Windows 95 uses this and enables you to run Win32 applications.


Windows created by Microsoft is for personal computers, the most widely used operating system. There are versions such as XP that are mainly used by home computers and for professional users Windows 2000.

Windows XP

Windows XP was released in 2001 and contained improvements on the previous Windows operating system. It was based on the Windows 2000 professional version and this made Windows XP more dependable.


Winsock (Window Sockets) is a term used to describe the files that enable Windows to have Internet access.16 bit applications will use WINSOCK.DLL whereas 64 bit applications use WSOCK32.DLL. However it is not necessary to know precisely how these function as only computer developers really need to know.


In computer terms Wireless can have several meanings, but the two most common are Wi-fi and Bluetooth. Wi-Fi wireless technology is used in computers that have a Wi-Fi card that can access a wireless router which is usually connected to a modem or DSL line for Internet access without the need for wires hence hte name wireless. Bluetooth on the other hand is a short range wireless device that can be used for printers and your computers mouse. In order to use Bluetooth you must make sure that all your devices and computer are Bluetooth enabled.


A Wizard is a guide within a program that takes you through parts of the program step-by-step. If you were creating a new document for example in Microsoft Word you would use the wizard to take you through the first steps.


WML (Wireless Markup Language) is the main format for WAP devices (the mojority of mobile phones for example use this) which is based on XML specifications.

Word Wrap

Word Wrap is the term used to describe the way in which a word processing application will automatically move a word that will overlap the documents default margins onto the line below.


There are two meanings for the term worm, the first is a virus that does not cause any damage to your files or computer but it multiplies and as it does so it takes up more and more space on your computers memory. Eventually this will cause your computer to run very slowly and even crash so it is important to have good Anti-virus protection to stop these unnoticed invaders. The second term refers to optical storage and stands for Write Once Read Many and this means a disc can be written on once but read many times over. One problem with WORMS discs is that unlike CD-Rs or DVD-Rs WORMs are only compatible with the system that they were written on meaning they cannot be read in other drives.


WPA (Wi-Fi Protected Access) is a means of securing Wi-Fi networks. Wi-Fi is an improvement on the WEP system as it changes the encryption/decryption keys used at the beginning and end of data transfer so that a user cannot make up their own to match the network and gain access. User authorition is also more complex with not only the MAC address being verified but several other aspects and this makes it much more difficult for an unauthorised computer accessing the network.


WWW or World Wide Web is not the Internet as many people think. It is in fact a term used to describe pages that are accessed via a browser.


WYSIWYG means What you See Is What You Get and it means that what you see on screen should be what you get when the screen is printed out. However for HTML this is not always what happens.


Any Intel processors created after the first 8086 are known generically as X86.


XHTML (Extensible Hypertext Markup Language) is another markup language that is similar to HTML but with a tighter principles.


XLL (Extensible Linking Language) is used to place links that directly point to a certain object on a Web page, such as an object or image and it ties in with W3Cs XML hyperlinks specification (it is the second part of it in fact)


XML or Extensible Markup Language a recommendation from W3C that enables programmers to create specific purpose markup languages. Its main use is to share data usually over the Internet through various information systems.


XSL or Extensible Stylesheet Language is used for interpreting XML document presentation and transformation.


Y2K (Year 200). There was much debate around the Y2K crisis that was more commonly know as the Millennium Bug and it was thought that computers around the world would crash and never recover as the year 2000 rolled round. This never happened.


Yahoo was created by David Filo and Jerry Yang and is a World Wide Web directory.


A Yobibyte is a single unit of data storage that can be expressed as 2 to the 80th power or 1,208,925,819,614,629,174,706,176 bytes.


A Yottabyte is the name used for a septillion bytes, it is more commonly used to describe a measurement of information or computer storage.


YPN or Yahoo Publishers Network is a Yahoo run program that webmasters can enroll in to enable Yahoo pay-per-click adverts on their websites.


A Zebibyte is a single unit of data storage that can be expressed as 2 to the 70th power or 1,180,591,620,717,411,303,424 bytes


A Zettabyte is very rarely used as it is so huge, it can be explained as 1,180,591,620,717,411,303,424 bytes.


ZIF or Zero Insertion Force is the term used to describe a type of CPU socket that is located on a computers motherboard. It enables users to upgrade their processor by pulling a lever and taking out the processor and replacing it. The new processor is then clipped back into place with no force required.


ZIP or Zone Information Protocol is a compression application used to size down files such as large word documents for ease of storage and transferring.

Zip Drive

Zip Drives are used for backing up personal data and files and are usually portable.

Zone File

Zone Files contain information about one or more domain names and is usually found on a name server. The information relates to a list of DNS records that shows the mapping between IP addresses and domain names. Zone files can easily be edited as they are in plain text and due to this they need to be highly protected on a secure sever and it is always good to have a backup of these files on a different computer.