The Computer Jargon Dictionary:

You certainly have noticed that there is lots and lots of strange gibberish associated with computers; and the industry just loves acronyms. Please bear with us for a moment while the table containing the definitions downloads.

The dictionary is divided into four sections, to speed up download and navigation: this is A-D (and numbers); click here for E-L; M-R; S-Z.

It says... It means...
404 error An error message received when you try to access a web page that either doesn't exist or is unavailable at the address you gave.
80211a, 80211b, 80211g, 80211i, 80211n Different standards for operating wireless networks (Wi-Fi). Loosely the higher the letter, the faster the speed. So far they are mostly incompatible with each other.
80286, 80386, 80486 (or 286, 386, 486) Three generations of PC processor, now pretty much obsolete, the ancestors of Intel's Pentium. The 286 was the earliest processor able to run (just about) a version of Windows, although the 386 was really the minimum to run it properly. The 486 was the earliest processor able to run Windows 95 - just about. Machines of this vintage cannot run modern versions of Windows at all, but many are still in use as basic word-processors or where a dedicated machine is required which doesn't need to be powerful.
ActiveX A Windows technology which allows programmers to do various things on your computer. Unfortunately it also allows hackers to do bad things to your computer, particularly via webpages in Internet Explorer, and is safest switched off. (In Internet Explorer go to Tools/Internet Options/Security and set the Security Zone slider for Internet to High. A few websites won't display quite as intended without it, but most bad ones won't be able to hijack you).
ADSL (Asymmetric Digital Subscriber Line) A method of connecting a computer to the internet over an ordinary phone line using ethernet office networking technology instead of an ordinary modem, which produces a much faster (broadband) connection. Asymmetric because it is faster from internet to PC than the other way (also true of a 56K modem).
Adware Software which displays advertisements on your computer. Sometimes installed as part of a "free" application, sometimes by stealth. See also Malware, Spyware.
AFAICS, AFAIK, AFAIR (As Far As I Can See/Know/Recall) Internet slang.
AGP (Advanced Graphics Port) A special slot on the PC motherboard for graphics cards, and the format of the cards themselves. Standard on new PCs from 1998. "AGP x 2" runs at twice the speed of the original AGP, AGP x 4 at four times the speed etc. Now being replaced by PCI Express.
AI (Artificial Intelligence) A program designed to respond "intelligently" to various situations, for example the computer opponent(s) in a game.
AIUI (As I Understand It) Internet slang.
always-on An internet connection which remains on 24/7 such as ADSL or cable, rather than only connecting on demand like a dialup.
AMD AMD is a leading manufacturer of processor chips for PCs, including the Athlon and Duron chips.
antispam An antispam program is used to filter out email spam, and sometimes to block it or complain about it.
antivirus Software which protects computers from viruses and suchlike. Has to be updated frequently to keep up with the latest threats, so is usually sold with a subscription which enables you to download updates from the internet.
AOL (America On Line) An Internet Service Provider, or ISP. AOL were in business as a large commercial bulletin board before the internet really took off. Now they are an ISP specialising in family-friendly internet access.
Apple The Apple Corporation makes the only successful personal computer which doesn't use Microsoft Windows, the Macintosh, and the popular iPod music player.
Applet A small program used to carry out a particular task, often on a web page. See Java.
Application Software used to carry out a particular task, such as word processing or desktop publishing. Essentially another word for program.
Architecture The basic design of a computer's hardware. Computers with different architecture, such as the PC and the Mac, cannot run each others' programs.
ASCII (American Standard Code for Information Interchange) An early and very basic format for text files, standard across pretty much all computers and mail systems. It only includes upper and lower case letters, numbers, and standard punctuation marks, but more sophisticated text formats still tend to be based on it. An ASCII file is a basic text-only file generated by a program like Notepad.
ATAPI (ATtAchment Packet Interface) An upgrade to EIDE which allows the hard disk controller to control CD drives as well. Almost all CD and DVD drives are controlled this way.
Athlon A PC processor - AMD, the other leading chip manufacturer's equivalent to Intel's Pentium. Like the Pentium, constantly being upgraded. You will often see a number such as 2700 following the word Athlon, which is a rough measure of the processor's speed - the higher the number, the faster the chip.
ATB (All The Best) Internet slang.
ATM (At The Moment) Internet slang.
Attachment A file sent by email is "attached" to the email. An attachment can be a picture, a word processor document, a program or any other type of file. You should never open an attachment if you are not sure what it is, because some viruses propagate as email attachments; but they can't infect your machine if you don't open the attachment.
AUP (Acceptable Use Policy) A document setting out what an Internet Service Provider deems an acceptable use of their services, usually published on their website. Typically it will forbid the publication of obscene or defamatory material, and sending email or newsgroup spam. If you violate your ISP's AUP, they will usually close your account down immediately.
autocorrect A feature in MS Word and other programs which automatically corrects your spelling, and even your grammar, as you type. Better switched off if you use obscure technical terms, or prefer your own interpretation of the rules of grammar, or else you are likely to find that it's "corrected" your text to something you didn't intend.
Avatar A picture or figure representing a person in an online environment.
Backup, back up A backup is an extra copy of your work, eg documents, pictures etc, saved onto a removable storage medium such as CD, DVD or magnetic tape, so that if your computer is stolen or breaks down you don't lose everything. Backup is a noun, back up is a verb.
Backwards-compatible A program (or system) designed to work with data generated by earlier versions of itself, even though the format may since have changed completely.
bandwidth A measure of total amount of data transferred over a period of time, often used to measure how busy a website is. A webhost will usually base its charges on the bandwidth a website uses, ie how much data per month is requested from it.
beat-'em-up A computer game in which you control one or more characters fighting onscreen using karate, kung-fu and so forth. Derives from shoot-'em-up.
biometric A system that examines biological things like fingerprints or retinas, usually for security purposes.
BIOS (Basic Input/Output System; pr. "by-oss") A program built into every PC for setting up very basic things, like how many hard and floppy disks you have and what type they are; the first thing that loads when you start your PC. You usually only need to access the BIOS if you are upgrading your hardware, eg adding more RAM or an extra disk drive, or setting a power-on password. BIOS settings are stored in a special type of memory called CMOS.
Bit The smallest unit of information in a computer, can either equal 0 or 1. Eight bits equal one byte.
Bitmap See bmp.
blog (weBLOG) A website documenting someone's life and/or thoughts.
Bluetooth A wireless communication system for PCs and other computing devices. However Bluetooth devices from different manufacturers won't always communicate with each other reliably, so it hasn't really taken off as the industry had hoped, and is now under threat from faster wireless technologies (see Wi-Fi).
bmp (BitMaP) A standard type of graphics file. An uncompressed format, so the files tend to be fairly big.
Boot, boot up Usually used to mean "start up the computer". Literally, the process of loading up the operating system and getting the computer ready for use. See Reboot. A "boot password" is a password you have to give to start up the computer.
Boot disk A floppy disk which holds a copy of the operating system, or enough of it to start the computer, useful if the computer won't start up properly from the hard disk. Because modern operating systems are so large, these days it is often a boot CD rather than a floppy.
Bot (roBOT) A semi-automated program, usually performing a function on the internet such as indexing webpages or sorting email.
bps (Bits Per Second) A measure of how quickly information is being transferred, usually via a modem or network. Divide by ten to get an approximation of the number of characters per second (cps). See also Kbps, Mbps.
BRB (Be Right Back) Internet slang.
Broadband Internet access over a connection much faster than an ordinary modem, such as ADSL or cable.
Browser A program used for viewing World Wide Web pages on the Internet. The most widely used is Microsoft's Internet Explorer, because it is built-in to Windows.
BTW (By The Way) Internet slang.
Buffer A temporary storage area for data, often used to "smooth out" incoming audio or video streams. Several seconds worth of material is stored in the buffer and it is then played back from there, so that if there is a brief interruption in the stream your music or video doesn't stop.
Bug Error, especially in a program, that has been missed in testing. The story goes that the original bug was an insect that got itself cremated inside an electrical circuit in an early computer, causing it to fail (and I don't suppose the insect enjoyed it much, either). It took them ages to figure out what was causing the problem, and when they eventually found the bug the story passed into legend.
Bulletin Board A semi-public area which computer users can connect to using a modem, to read and post messages and/or exchange files. Now largely replaced by websites.
Burn Create a CD or DVD.
Byte A basic unit of measurement for pieces of information; the space required to store one character. See also Bit, Kilobyte, Megabyte, Gigabyte, Terabyte.
Cable An always-on high speed internet connection similar to ADSL but using cable TV technology instead of a phoneline.
Cache A temporary storage area for frequently or recently used data, either in memory, on your hard disk or the internet. For example, if you go back to a webpage you have recently visited, your PC will usually be able to display it from the internet cache on your hard disk, so it won't need to download it from the internet again.
CAD (Computer Aided Design) Software used to produce complex technical drawings by designers and engineers.
CCD (Charge Coupled Device) The component of a scanner or digital camera which actually takes the pictures. The quality of image it is capable of is usually measured in Megapixels - the higher the number, the more detailed the image.
CD Burner A CD drive that can create ("burn") CDs.
CD-ROM, CD-R (Compact Disk-Read Only Memory) A misnomer, as strictly speaking it is not memory but storage. Identical to standard music CDs. Currently the most popular medium for releasing programs on, as it can hold literally hundreds of times as much information as a standard floppy disk, about 650 Megabytes in total. Once a CD-ROM has been created its contents cannot be changed. Now starting to be replaced by DVD.
CD-RW (Compact Disk-ReWriter) A CD drive which can create CDs, either audio or data, using special rewriteable CDs which are also often called CD-RWs. A CD-RW drive can also create ordinary CDs, though not rewrite them.
Celeron A PC processor - Intel's budget chip, cheaper than the Pentium, but also less powerful.
Character A letter of the alphabet, number, space or punctuation mark is a character.
Chatroom A website where you can meet and chat live (via the keyboard) with other internet users. Most such websites have multiple "rooms", each dedicated to a particular topic or theme.
Chip A silicon wafer with millions of tiny circuits engraved on it - what computers are made of..
Clipboard A temporary storage area in Windows. When you cut (Ctrl-X) or copy (Ctrl-C) highlighted text, documents or whatever in Windows they are sent to the clipboard; when you paste (Ctrl-V) they are copied from the clipboard to the cursor position. Sending something to the clipboard automatically overwrites its previous contents.
Cluster Data stored on a disk is spread across a number of clusters, small physical areas on the disk. How big they are depends on the way the disk is formatted - generally a few kilobytes each.
CMOS (Complementary Metal Oxide Semiconductor; pr. "see-moss") A special type of memory which retains its data when the PC is switched off, used to store settings for things like what type of hard disk you have, and how much memory. The settings are accessed via the BIOS.
CMYK (Cyan, Magenta, Yellow, Keystone black ) The standard four colours used by most printers - almost any colour can be created out of these. See also RGB.
codec (COmpressor/DECompressor) A small piece of computer code that tells the computer how to decode particular types of information, usually video files. If your video player won't play a particular format, you can usually download and install a codec which will tell it how from the internet.
Compatible Compatible pieces of equipment can work together; incompatible ones can't.
Compression A way of making files smaller, either to fit into restricted storage space or to speed up transmission over the Internet. Popular compression standards include JPEG and GIF for pictures, MP3 for music files, MPEG for movies, and zip for just about everything else.
Console Nowadays usually refers to a dedicated gaming computer such as the Playstation or X-Box. Originally meant a terminal connected to a mainframe computer.
Cookie A small data file stored on your computer by a website, in theory to allow it to "remember" your preferences, but in practise mostly used to track which adverts you have seen. You can set most browsers to reject all cookies, or to ask your permission before storing them, but this can generate multiple error messages on some websites and is generally more hassle than it's worth - they are pretty harmless.
cps (Characters Per Second) A measure of how quickly information, particularly text, is being transferred over a modem link or network. See also bps.
CPU (Central Processing Unit) The nerve centre of the computer : everything flows through it. Often just called "the processor". The best known PC processors are Intel's Pentium and AMD's Athlon.
Crack, cracked A crack is a small program intended to defeat software's copy protection, thus allowing unlicensed copies to be made - stealing it, in effect. Software that is distributed with its copy protection disabled or bypassed has been "cracked".
Crash When a computer program or operating system stops working completely or almost completely it (or the computer) is said to have "crashed". When a computer crashes it usually needs to be rebooted before it can be used again. See also lockup.
Crawler A program that indexes pages on the World Wide Web for search engines.
CRT (Cathode Ray Tube) The imaging technology used in most desktop monitors. Provides an excellent colour display, but is extremely bulky and is now being gradually supplanted by TFT.
CSS (Cascading Style Sheets) A set of HTML commands used to control the style of web pages, much more complex than the <FONT> tag-set it is intended to replace, but also more powerful and particularly useful for retaining a uniform style across a large website. Generally only used by professional web designers.
Cyberspace Loosely speaking, the internet, and virtual places thereon.
Cybersquatter Someone who buys up internet domain names in order to sell them on at a profit.
Data Any information created by a user, such as documents, pictures or sound recordings.
Database A program used for organising any kind of information on a computer into a searchable form, anything from a list of contacts to a complex stock control and accounts system.
DDR (Double Data Rate) A fast type of RAM for a PC, originally only used on high performance graphics cards but now being used for general memory in most high-end PCs. DDR2 is a yet faster version.
Default A default setting is one you haven't changed - what a program will do (or use) if you don’t tell it any different. "Accept the defaults" means leave any settings as they are.
Desktop A computer designed to sit on a desk (as opposed to a laptop). In Windows, it also means the screen you see when you aren't running any programs, with "My Computer", the Recycle Bin and so on.
Digital Literally "to do with numbers". Often used to describe a device using computer technology to replace older, traditional technologies. For example, a digital camera is one that stores images electronically rather than on chemical film.
DIMM (Dual In-line Memory Module; pr. "dim") A module of RAM (memory) for a PC, replacing the older SIMM specification.
Directory An area on a disk for storing files, particularly in DOS. Usually called a folder in Windows.
Disk Generic term for a type of storage device, such as a hard disk or a floppy disk (diskette). So called because the important part, where the information is actually stored, is circular, although you can't see it because it is hidden away inside a protective shell.
Diskette Also known as a floppy disk. Called a diskette because it was smaller than the original huge floppy disks, now long obsolete.
DNS (Domain Name Service/System) An internet service that converts a human web address such as into the numeric address that computers use, called the IP address. "Can't resolve DNS" usually means that this conversion has failed and therefore the website can't be found.
Domain An internet address owned by a company, organisation or individual, such as, or See also TLD.
Dongle A small hardware device used for copy protection with some software. The dongle must be plugged in to a port on the computer, often the printer port, or the software won't function. They are often unpopular with users because if the dongle gets lost or broken, the software won't function.
DOS (Disk Operating System; pr. "doss") Usually refers to MS-DOS, which was the standard operating system for PCs until Windows 95 came out, now pretty much obsolete. Controlled by typing in text commands and has several serious limitations, but requires a much less powerful computer than Windows 95.
DoS (Denial of Service) A form of attack on (usually) an internet service, which aims to prevent the service from operating properly, often by bombarding it with more information than it can process. See also Mailbomb.
Download To transfer information (files) from a network (such as the Internet) onto a user's PC. See also upload.
dpi (Dots Per Inch) A measure of picture quality, often used to measure printer capabilities. The higher the number, the better the quality.
Driver A small program used by the operating system to control hardware such as a sound or video card. Often downloading the latest driver for a device from the manufacturer's website will improve its functionality.
DRM (Digital Rights Management) Software intended to prevent the unauthorised duplication of copyrighted video or audio, usually built into a computer's operating system.
Dual core, dual-core PC processors which have two complete processors on the same chip, allowing computers to handle multiple tasks faster. See also quad-core.
Dual layer A technology allowing two layers of data to be written to a DVD instead of the usual one, thus increasing its capacity.
DVD (Digital Versatile Disk) A more advanced version of the standard CD which can hold far more information, now standard on most new PCs. Widely used for high-quality digital movies. DVD drives can usually also read ordinary CDs.
DVD RW, DVD Writer (Digital Versatile Disk ReWriter) A DVD drive that can create ("write") rewriteable DVDs. There are several competing formats at the moment, but most recent drives support more than one format. It is likely that one of these formats will become standard in time, but at the moment it is not clear which. To add to the confusion, they tend to have very similar names : for example DVD+RW and DVD-RW are completely different formats, and incompatible with each other.
DVI (Direct Video Interface) A special type of connector for computer monitors, particularly flat panels.
The Computer Jargon Dictionar

That was A-D (+ numbers); click here for E-L; M-R; S-Z.

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