Dictionary of computer jargon E-L

A dictionary of computer jargon

Compiled by Jon Storm.
2022 edition.

Thanks for visiting! You will certainly have noticed that there is lots and lots of strange gibberish associated with computers; and the industry just loves acronyms. This is a guide to some of the more common ones.

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

It says... It means...

E-commerce Conducting business over the internet, and particularly the World Wide Web.

Email (or e-mail) (Electronic mail ; pr. "ee-mail") A way to send messages between computers, or more to the point their users, either over a network or the Internet. E-mail is usually just text, but can have pictures or other files attached. See Attachment.

Emoji Small pictures used to convey emotions in text

Emoticon (EMOTion ICON) Similar to emojis, but created using text characters. The most popular is the smiley :-) or :) (look at it sideways), but there are lots of variations including the sad face :-( , the wink ;-) , and the astonished face :-0 .

Encrypt, encryption Coding data so that it can't be read by hackers etc when transmitted over the internet. For example, any reputable website selling goods by credit card will encrypt your credit card number and personal details.

Ethereum The second most popular cryptocurrency (after Bitcoin).

Ethernet The system used to connect computers to a network or the internet with a physical cable, including most broadband internet connections. Usually much faster than a wireless connection.

Excel The most popular spreadsheet program for PCs, part of the Microsoft Office suite.

exe (or .exe) (EXEcutable; pr. "exie", "dot exie" ) A file which is usually the main part of a program. A program may consist of just an exe file and nothing else, or there may be dozens of files, including more .exes.

Expansion card (or board) A circuitboard which can be plugged in to an expansion slot on the PC's motherboard, to give the PC extra capabilities. A lot of the features originally provided by expansion cards, like sound, graphics and network connections, are now built in.

Facebook A popular social media site on which you can share messages, pictures and videos with friends and acquaintances.

FAQ (Frequently Asked Questions). A document on a website or in a newsgroup which gives answers to common problems and questions. Look for an FAQ if you have a problem with something, before you email or phone support.

FAT (File Allocation Table; pr. "fat") A sort of index of where data is stored on a hard disk, used by the operating system.

FDD (Fixed Disk Drive, Floppy Disk Drive). The slot on the PC which accepts floppy disks, almost always referred to as "Drive A:" by the computer. Now obsolete.

FFS (For F***'s Sake) Internet slang, not suitable for polite company.

File All information on a computer is stored in files, whether it is part of a program, a document created by a user, a picture, or anything else. Most software is made up of dozens, sometimes hundreds, of different files.

File server A type of computer used on networks to provide files and other services to other computers. Often just called a server.

Filter A device which allows you to use an ordinary phone over a telephone line set up for an ADSL internet connection. Also called a microfilter.

Firefox A popular alternative browser, available free from Mozilla, as an alternative to the browser built into your operating system.

Firewall Originally a dedicated computer between you and the internet, preventing hackers, spammers and similar undesirables from taking over your PC. Now often just a program running on your PC, performing the same task.

Firewire A standard for fast data transfer created by Apple, now replaced by USB for most purposes.

Flame Internet slang for an email, forum or newsgroup post insulting or telling someone off.

Flamewar A public trading of insults in a newsgroup or forum. Sometimes flamewars get so out of hand that there are hundreds of flames in the newsgroup and almost nothing else.

Flash A technology for displaying animations and videos on webpages, now obsolete

Flash drive A removable data storage device, usually thumb sized and plugged into a USB port.

Floppy disk Also known as a diskette. Now obsolete. Originally called floppy disks because they were round and non-rigid, but later the actual floppy disk was enclosed inside a rigid, near-square protective casing.

FOAD (<bleep> Off And Die) Internet slang. Pretty self-explanatory really.

Folder An area on a disk for storing files in. Folders can also contain other folders, which in turn can contain more folders, and so on almost to infinity.

Font Another word for typeface, ie the style of lettering.

Forum A public or semi-public area on a website or bulletin board where you can read and post messages on a particular topic, allowing public debate.

FPS
1 (Frames Per Second) A measure of the smoothness and quality of animations, particularly in computer games. The more frames per second, the better the quality.

2 (First Person Shooter) A computer game where you shoot things, played from a first person perspective, ie with you standing behind the gun(s). Also known as a shoot-'em-up.

FTP (File Transfer Protocol). A way of transferring files to or from an internet server. Often how you upload webpages to the internet.

GB See Gigabyte.

GHz Gigahertz - billions of cycles per second. Often used as a measurement of a PC processor chip's speed and power, with bigger numbers meaning a bit more speed, and a higher price. 1000 MHz = 1.0 GigaHertz. See also MHz.

GIF (Graphics Interchange Format) A popular type of compressed graphics (picture) file, widely used on the web. Best for artwork with 256 colours or less. See also jpg, compression.

Gigabyte (or Gig) Unit of measurement for pieces of information : approximately 1 billion bytes, 1 million kilobytes, or 1000 megabytes. Hard disk sizes are usually measured in gigabytes. Often shortened to "GB", "Gig" or just G.

GIGO (Garbage In Garbage Out; pr. "guy-go") A fundamental principle of computing, that if you feed a computer bad data, you will get bad results, even if the program is working perfectly.

Google Started out as search engine and rapidly became so much better at it than everyone else that "to google" was (and is) widely used to mean "to look up via the internet". Now a huge, rich and influential corporation with fingers in many pies, owners of the Android operating system for smartphones and tablets. Its headquarters are in California and it has offices and data centers all over the world.

GPU (Graphics Processing Unit). A computer circuit board which plugs into the motherboard and is responsible for drawing the graphics which appear on your screen. Also widely used for "mining" cryptocurrency.

Graphics A catch-all term for anything involving drawing images on a PC screen. A game with great graphics is one that is visually spectacular.

GUI (Graphical User Interface; pr. "gooey") program controls that are represented pictorially, with symbols, buttons and so forth, and mostly controlled by pointing and clicking with a mouse or tapping a touchscreen rather than having to type in text commands. Almost all modern software is GUI controlled. (see also Windows, WYSIWYG).

Hacker Person who uses computers to access ("hack") systems they are not supposed to have access to, eg other people's financial details, personnel files, military secrets etc. Hacking can get you arrested.

HAND (Have A Nice Day) Internet slang, often used ironically.

Hard disk A computer's main storage for programs and data. Originally named to distinguish it from floppy disks. Almost all PCs are fitted with hard disks, sometimes more than one. The first (or only) hard disk is usually called C: by the computer, for historical reasons. Now being superseded by SSDs, which are much faster.

Hardware The physical parts of a computer.

HD, HDD (Hard Disk Drive) The main data storage unit in a computer. See hard disk.

hodl (Hold On for Dear Life) slang widely used by cryptocurrency fans, encouraging each other to hold on to their cryptocurrency when it is fluctuating wildly in value.

Homepage A page on the World Wide Web. Confusingly "homepage" is used indiscriminately to describe several slightly different things : an amateur's website; the front or main page of any website; or the page which your browser first goes to when you start it up.

Hotspot A location where a computer can connect to a wireless network (see Wi-Fi).

HTH (Hope This Helps) Internet slang, often added at the end of an email or newsgroup post answering a question.

HTML (HyperText Markup Language) The system used for creating World Wide Web pages, ordinary text with commands for special effects like pictures, colour and links enclosed between < > symbols. You can add the various HTML commands to ordinary text by hand or have it generated for you by software, usually with a specialist editor like Dreamweaver.

http, https (HyperText Transfer Protocol (Secure)) The protocol or "language" computers use to send web pages over the internet. Almost every WWW address starts "http://", though many browsers understand if you omit it. If it has an S after the HTTP the connection is secure.

Hub A basic device for connecting computers together to form a network. See Router.

Hung If a computer (or sometimes just a program) gets completely stuck and refuses to do anything, it has hung. See also lockup.

Hyperlink Any kind of link on a webpage. Unless you typed this page's URL in by hand, you got here by clicking on a hyperlink.

Hypertext What web pages are made of.

IANAL (I Am Not A Lawyer) Internet slang. Amazing how often this one comes up.

IBM (International Business Machines) The company that designed and built the first PCs, now specialising in technology services. They stopped building PCs a long time ago.

Icon Small pictogram either representing a file, or providing shortcuts for carrying out common tasks such as saving and printing inside an application.

IDE (Integrated Drive Electronics ) A type of PC hard disk, now obsolete, the foreunner of EIDE.

IE (Internet Explorer) Microsoft's origianl web browser, now obsolete

IIRC (If I Recall Correctly) Internet slang.

IM (Instant Messenging) A program that allows you to "chat" live via keyboard over the internet.

IMAP (Internet Message Access Protocol) A system for checking email that leaves the email on the server instead of deleting it after it has been downloaded, widely used in tablets and phones and becoming more popular on desktop and laptop computers.

IMO, IMHO (In My (Honest) Opinion) Internet slang.

Inkjet A popular colour printer technology, which works by squirting tiny jets of ink onto paper with great precision.

Install Most programs need to be installed before they can be used, though a few can be run from a thumb drive

Instagram A popular social media site on which you can share pictures and videos with friends and acquaintances.

Intel The Intel Corporation is the leading manufacturer of processor chips for PCs.

Internet
A vast worldwide network of computers, accessible to anyone with a computer and a broadband connection. Provides access to e-mail and the World Wide Web. The Internet grew out of the need of academics to swap information with colleagues all over the world, and of the US military's need for a computer and communications network that couldn't easily be knocked out. As a result it is very difficult to censor, since anything placed on the World Wide Web from anywhere is available everywhere in the world.

Intranet A private miniature internet, usually belonging to a single company or organization, connecting the organization's computers together while (usually) restricting access from the internet proper. Often just called "the network".

iOS (iphone Operating System) The operating system for Apple's smartphones (iPhone) and tablets (iPad).

IP (Internet Protocol ) A protocol (computer language) which computers use to communicate with and over the internet.

IP address (Internet Protocol address) A unique number assigned to any computer connected to the internet, including yours, in the format 255.255.255.255. Each of the four blocks of numbers can be any value from 0 to 255. They can either be assigned permanently ("static IP") or per session ("dynamic IP"). Most ISPs assign them dynamically, ie when you connect to the internet.

iPad A popular tablet computer from Apple.

iPhone An extremely popular smartphone from Apple.

iPod The Apple Corporation's massively successful portable music player, no longer manufactured as a standalone device because it is built into the iPhone. See also iTunes.

ISA (Industry Standard Architecture; pr."icer") A once-common type of PC expansion card, now obsolete; see also EISA, PCI.

ISDN
(Integrated Services Digital Network ) An early high speed (for its time) internet connection system mainly aimed at business, now largely obsolete. Requires a special type of modem called a Terminal Adaptor.

ISP (Internet Service Provider) A company which provides a connection to the internet, or internet services.

ISTM (It Seems To Me) Internet slang.

ISTR (I Seem To Recall) Internet slang.

IT (Information Technology) What computers are all about - using technology to manage information. The computer industry is often called the IT industry.

iTunes The Apple Corporation's online music store and program,, where you can download millions of digital music tracks and movies, now mostly rebranded as Apple Music. Apple go to a lot of trouble to make it difficult and inconvenient to buy digital content from anywhere else on their devices.

Java A programming language used to create small programs called applets, often to produce special effects on web pages.

Javascript A set of program instructions, vaguely similar to Java but not actually related, written straight into the HTML of a webpage instead of as an applet.

JPEG, jpg (Joint Picture [Experts] Group; pr. "jay-peg") A standard type of compressed graphics file, widely used on the WWW. Particularly good for photographs. See also compression.

Killer app (Killer application) A program that is so obviously massively useful to someone that they will rush out and buy it immediately, and if necessary a computer to run it on.

Kbps (KiloBits Per Second) A measure of speed of information flow, usually over a modem. A Kilobit is a thousand bits. See also bps, Mbps.

Kilobyte Unit of measurement for pieces of information : actually 1024 Bytes (characters), but in practice almost always rounded down to 1000. Often written as just K, eg 250 K is 250 Kilobytes (250,000 bytes/characters - well not exactly, but close enough). See also Megabyte, Gigabyte, Terabyte.

LAN (Local Area Network; pr."lan") A network of computers connected together, usually in a single department or building. See also WAN.

Laptop A portable PC, with system unit, screen and keyboard crammed into one package. They can do pretty much everything a desktop PC can do, but are more expensive because of the extra miniaturisation required. Also called a notebook.

Laser printer, laserprinter A high speed printer intended mainly for office use, usually better for text than graphics, especially in colour.

LCD (Liquid Crystal Display) A type of computer screen, originally used only on laptops but now widely used for desktop PCs and televisions.

Linux A rival PC operating system to Microsoft Windows, but unlike Windows it is "open source", which means that anyone can create their own version of it without having to pay royalties, and requires a much less powerful computer. There are several slightly different versions. Requires some technical knowledge to use.

LMAO (Laughing My Ass Off) Internet slang.

Lockup, locked up An event which causes a computer to get stuck and refuse to do anything is a lockup. The computer is then said to be hung or locked up.

LOL (Laughing Out Loud) Internet slang.

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

Didn't find what you were looking for? Sorry about that. Send an email to dictionary22 at jonstorm.com and I'll try and include it in the next revision. Your feedback is much appreciated!

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It says...	It means...
E-commerce	Conducting business over the internet, and particularly the World Wide Web.
Email (or e-mail)	(Electronic mail ; pr. "ee-mail") A way to send messages between computers, or more to the point their users, either over a network or the Internet. E-mail is usually just text, but can have pictures or other files attached. See Attachment.
Emoji	Small pictures used to convey emotions in text
Emoticon	(EMOTion ICON) Similar to emojis, but created using text characters. The most popular is the smiley :-) or :) (look at it sideways), but there are lots of variations including the sad face :-( , the wink ;-) , and the astonished face :-0 .
Encrypt, encryption	Coding data so that it can't be read by hackers etc when transmitted over the internet. For example, any reputable website selling goods by credit card will encrypt your credit card number and personal details.
Ethereum	The second most popular cryptocurrency (after Bitcoin).
Ethernet	The system used to connect computers to a network or the internet with a physical cable, including most broadband internet connections. Usually much faster than a wireless connection.
Excel	The most popular spreadsheet program for PCs, part of the Microsoft Office suite.
exe (or .exe)	(EXEcutable; pr. "exie", "dot exie" ) A file which is usually the main part of a program. A program may consist of just an exe file and nothing else, or there may be dozens of files, including more .exes.
Expansion card (or board)	A circuitboard which can be plugged in to an expansion slot on the PC's motherboard, to give the PC extra capabilities. A lot of the features originally provided by expansion cards, like sound, graphics and network connections, are now built in.
Facebook	A popular social media site on which you can share messages, pictures and videos with friends and acquaintances.
FAQ	(Frequently Asked Questions). A document on a website or in a newsgroup which gives answers to common problems and questions. Look for an FAQ if you have a problem with something, before you email or phone support.
FAT	(File Allocation Table; pr. "fat") A sort of index of where data is stored on a hard disk, used by the operating system.
FDD	(Fixed Disk Drive, Floppy Disk Drive). The slot on the PC which accepts floppy disks, almost always referred to as "Drive A:" by the computer. Now obsolete.
FFS	(For F*'s Sake) Internet slang, not suitable for polite company.
File	All information on a computer is stored in files, whether it is part of a program, a document created by a user, a picture, or anything else. Most software is made up of dozens, sometimes hundreds, of different files.
File server	A type of computer used on networks to provide files and other services to other computers. Often just called a server.
Filter	A device which allows you to use an ordinary phone over a telephone line set up for an ADSL internet connection. Also called a microfilter.
Firefox	A popular alternative browser, available free from Mozilla, as an alternative to the browser built into your operating system.
Firewall	Originally a dedicated computer between you and the internet, preventing hackers, spammers and similar undesirables from taking over your PC. Now often just a program running on your PC, performing the same task.
Firewire	A standard for fast data transfer created by Apple, now replaced by USB for most purposes.
Flame	Internet slang for an email, forum or newsgroup post insulting or telling someone off.
Flamewar	A public trading of insults in a newsgroup or forum. Sometimes flamewars get so out of hand that there are hundreds of flames in the newsgroup and almost nothing else.
Flash	A technology for displaying animations and videos on webpages, now obsolete
Flash drive	A removable data storage device, usually thumb sized and plugged into a USB port.
Floppy disk	Also known as a diskette. Now obsolete. Originally called floppy disks because they were round and non-rigid, but later the actual floppy disk was enclosed inside a rigid, near-square protective casing.
FOAD	(<bleep> Off And Die) Internet slang. Pretty self-explanatory really.
Folder	An area on a disk for storing files in. Folders can also contain other folders, which in turn can contain more folders, and so on almost to infinity.
Font	Another word for typeface, ie the style of lettering.
Forum	A public or semi-public area on a website or bulletin board where you can read and post messages on a particular topic, allowing public debate.
FPS	1 (Frames Per Second) A measure of the smoothness and quality of animations, particularly in computer games. The more frames per second, the better the quality. 2 (First Person Shooter) A computer game where you shoot things, played from a first person perspective, ie with you standing behind the gun(s). Also known as a shoot-'em-up.
FTP	(File Transfer Protocol). A way of transferring files to or from an internet server. Often how you upload webpages to the internet.
GB	See Gigabyte.
GHz	Gigahertz - billions of cycles per second. Often used as a measurement of a PC processor chip's speed and power, with bigger numbers meaning a bit more speed, and a higher price. 1000 MHz = 1.0 GigaHertz. See also MHz.
GIF	(Graphics Interchange Format) A popular type of compressed graphics (picture) file, widely used on the web. Best for artwork with 256 colours or less. See also jpg, compression.
Gigabyte (or Gig)	Unit of measurement for pieces of information : approximately 1 billion bytes, 1 million kilobytes, or 1000 megabytes. Hard disk sizes are usually measured in gigabytes. Often shortened to "GB", "Gig" or just G.
GIGO	(Garbage In Garbage Out; pr. "guy-go") A fundamental principle of computing, that if you feed a computer bad data, you will get bad results, even if the program is working perfectly.
Google	Started out as search engine and rapidly became so much better at it than everyone else that "to google" was (and is) widely used to mean "to look up via the internet". Now a huge, rich and influential corporation with fingers in many pies, owners of the Android operating system for smartphones and tablets. Its headquarters are in California and it has offices and data centers all over the world.
GPU	(Graphics Processing Unit). A computer circuit board which plugs into the motherboard and is responsible for drawing the graphics which appear on your screen. Also widely used for "mining" cryptocurrency.
Graphics	A catch-all term for anything involving drawing images on a PC screen. A game with great graphics is one that is visually spectacular.
GUI	(Graphical User Interface; pr. "gooey") program controls that are represented pictorially, with symbols, buttons and so forth, and mostly controlled by pointing and clicking with a mouse or tapping a touchscreen rather than having to type in text commands. Almost all modern software is GUI controlled. (see also Windows, WYSIWYG).
Hacker	Person who uses computers to access ("hack") systems they are not supposed to have access to, eg other people's financial details, personnel files, military secrets etc. Hacking can get you arrested.
HAND	(Have A Nice Day) Internet slang, often used ironically.
Hard disk	A computer's main storage for programs and data. Originally named to distinguish it from floppy disks. Almost all PCs are fitted with hard disks, sometimes more than one. The first (or only) hard disk is usually called C: by the computer, for historical reasons. Now being superseded by SSDs, which are much faster.
Hardware	The physical parts of a computer.
HD, HDD	(Hard Disk Drive) The main data storage unit in a computer. See hard disk.
hodl	(Hold On for Dear Life) slang widely used by cryptocurrency fans, encouraging each other to hold on to their cryptocurrency when it is fluctuating wildly in value.
Homepage	A page on the World Wide Web. Confusingly "homepage" is used indiscriminately to describe several slightly different things : an amateur's website; the front or main page of any website; or the page which your browser first goes to when you start it up.
Hotspot	A location where a computer can connect to a wireless network (see Wi-Fi).
HTH	(Hope This Helps) Internet slang, often added at the end of an email or newsgroup post answering a question.
HTML	(HyperText Markup Language) The system used for creating World Wide Web pages, ordinary text with commands for special effects like pictures, colour and links enclosed between < > symbols. You can add the various HTML commands to ordinary text by hand or have it generated for you by software, usually with a specialist editor like Dreamweaver.
http, https	(HyperText Transfer Protocol (Secure)) The protocol or "language" computers use to send web pages over the internet. Almost every WWW address starts "http://", though many browsers understand if you omit it. If it has an S after the HTTP the connection is secure.
Hub	A basic device for connecting computers together to form a network. See Router.
Hung	If a computer (or sometimes just a program) gets completely stuck and refuses to do anything, it has hung. See also lockup.
Hyperlink	Any kind of link on a webpage. Unless you typed this page's URL in by hand, you got here by clicking on a hyperlink.
Hypertext	What web pages are made of.
IANAL	(I Am Not A Lawyer) Internet slang. Amazing how often this one comes up.
IBM	(International Business Machines) The company that designed and built the first PCs, now specialising in technology services. They stopped building PCs a long time ago.
Icon	Small pictogram either representing a file, or providing shortcuts for carrying out common tasks such as saving and printing inside an application.
IDE	(Integrated Drive Electronics ) A type of PC hard disk, now obsolete, the foreunner of EIDE.
IE	(Internet Explorer) Microsoft's origianl web browser, now obsolete
IIRC	(If I Recall Correctly) Internet slang.
IM	(Instant Messenging) A program that allows you to "chat" live via keyboard over the internet.
IMAP	(Internet Message Access Protocol) A system for checking email that leaves the email on the server instead of deleting it after it has been downloaded, widely used in tablets and phones and becoming more popular on desktop and laptop computers.
IMO, IMHO	(In My (Honest) Opinion) Internet slang.
Inkjet	A popular colour printer technology, which works by squirting tiny jets of ink onto paper with great precision.
Install	Most programs need to be installed before they can be used, though a few can be run from a thumb drive
Instagram	A popular social media site on which you can share pictures and videos with friends and acquaintances.
Intel	The Intel Corporation is the leading manufacturer of processor chips for PCs.
Internet	A vast worldwide network of computers, accessible to anyone with a computer and a broadband connection. Provides access to e-mail and the World Wide Web. The Internet grew out of the need of academics to swap information with colleagues all over the world, and of the US military's need for a computer and communications network that couldn't easily be knocked out. As a result it is very difficult to censor, since anything placed on the World Wide Web from anywhere is available everywhere in the world.
Intranet	A private miniature internet, usually belonging to a single company or organization, connecting the organization's computers together while (usually) restricting access from the internet proper. Often just called "the network".
iOS	(iphone Operating System) The operating system for Apple's smartphones (iPhone) and tablets (iPad).
IP	(Internet Protocol ) A protocol (computer language) which computers use to communicate with and over the internet.
IP address	(Internet Protocol address) A unique number assigned to any computer connected to the internet, including yours, in the format 255.255.255.255. Each of the four blocks of numbers can be any value from 0 to 255. They can either be assigned permanently ("static IP") or per session ("dynamic IP"). Most ISPs assign them dynamically, ie when you connect to the internet.
iPad	A popular tablet computer from Apple.
iPhone	An extremely popular smartphone from Apple.
iPod	The Apple Corporation's massively successful portable music player, no longer manufactured as a standalone device because it is built into the iPhone. See also iTunes.
ISA	(Industry Standard Architecture; pr."icer") A once-common type of PC expansion card, now obsolete; see also EISA, PCI.
ISDN	(Integrated Services Digital Network ) An early high speed (for its time) internet connection system mainly aimed at business, now largely obsolete. Requires a special type of modem called a Terminal Adaptor.
ISP	(Internet Service Provider) A company which provides a connection to the internet, or internet services.
ISTM	(It Seems To Me) Internet slang.
ISTR	(I Seem To Recall) Internet slang.
IT	(Information Technology) What computers are all about - using technology to manage information. The computer industry is often called the IT industry.
iTunes	The Apple Corporation's online music store and program,, where you can download millions of digital music tracks and movies, now mostly rebranded as Apple Music. Apple go to a lot of trouble to make it difficult and inconvenient to buy digital content from anywhere else on their devices.
Java	A programming language used to create small programs called applets, often to produce special effects on web pages.
Javascript	A set of program instructions, vaguely similar to Java but not actually related, written straight into the HTML of a webpage instead of as an applet.
JPEG, jpg	(Joint Picture [Experts] Group; pr. "jay-peg") A standard type of compressed graphics file, widely used on the WWW. Particularly good for photographs. See also compression.
Killer app	(Killer application) A program that is so obviously massively useful to someone that they will rush out and buy it immediately, and if necessary a computer to run it on.
Kbps	(KiloBits Per Second) A measure of speed of information flow, usually over a modem. A Kilobit is a thousand bits. See also bps, Mbps.
Kilobyte	Unit of measurement for pieces of information : actually 1024 Bytes (characters), but in practice almost always rounded down to 1000. Often written as just K, eg 250 K is 250 Kilobytes (250,000 bytes/characters - well not exactly, but close enough). See also Megabyte, Gigabyte, Terabyte.
LAN	(Local Area Network; pr."lan") A network of computers connected together, usually in a single department or building. See also WAN.
Laptop	A portable PC, with system unit, screen and keyboard crammed into one package. They can do pretty much everything a desktop PC can do, but are more expensive because of the extra miniaturisation required. Also called a notebook.
Laser printer, laserprinter	A high speed printer intended mainly for office use, usually better for text than graphics, especially in colour.
LCD	(Liquid Crystal Display) A type of computer screen, originally used only on laptops but now widely used for desktop PCs and televisions.
Linux	A rival PC operating system to Microsoft Windows, but unlike Windows it is "open source", which means that anyone can create their own version of it without having to pay royalties, and requires a much less powerful computer. There are several slightly different versions. Requires some technical knowledge to use.
LMAO	(Laughing My Ass Off) Internet slang.
Lockup, locked up	An event which causes a computer to get stuck and refuse to do anything is a lockup. The computer is then said to be hung or locked up.
LOL	(Laughing Out Loud) Internet slang.