Glossary of Computer Terms

Computer Terms Glossary

This page is meant to serve as a guide to the vast quantity of computer terms and acronyms in common use for the casual computer user. It is divided into two main sections, the first is dedicated to the basics and is meant more for beginners, while the second is meant instead to be used as a reference. In reality many of the terms in the second section are still quite common; the first section was deliberately kept as short as possible.

Terms in the second section may be looked up by either using the "find in page" function of your browser, or by appending "#term" (without the quotes and where term is the term of interest) to the "URL" or "go to" section of your browser, keeping in mind that case matters. The best method of searching for a term though is to use the Search Interface that will return not only the specific term sought but also other entries that reference it. Be aware that the terms referenced in the second part of this page will freely assume familiarity with the first part.

If you are instead actually trying to figure out what a particular filename extension means, you might instead try the filename extensions page.

If you want something added or see a problem with something already here (but keep in mind this guide is not meant to be overly technical) please send .


The concept behind an e-book is that it should provide all the functionality of an ordinary book but in a manner that is (overall) less expensive and more environmentally friendly. The actual term e-book is somewhat confusingly used to refer to a variety of things: custom software to play e-book titles, dedicated hardware to play e-book titles, and the e-book titles themselves. Individual e-book titles can be free or commercial (but will always be less expensive than their printed counterparts) and have to be loaded into a player to be read. Players vary wildly in capability level. Basic ones allow simple reading and bookmarking; better ones include various features like hypertext, illustrations, audio, and even limited video. Other optional features allow the user to mark-up sections of text, leave notes, circle or diagram things, highlight passages, program or customize settings, and even use interactive fiction. There are many types of e-book; a couple popular ones include the Newton book and Palm DOC.
E-mail is short for electronic mail. It allows for the transfer of information from one computer to another, provided that they are hooked up via some sort of network (often the Internet. E-mail works similarly to FAXing, but its contents typically get printed out on the other end only on demand, not immediately and automatically as with FAX. A machine receiving e-mail will also not reject other incoming mail messages as a busy FAX machine will; rather they will instead be queued up to be received after the current batch has been completed. E-mail is only seven-bit clean, meaning that you should not expect anything other than ASCII data to go through uncorrupted without prior conversion via something like uucode or bcode. Some mailers will do some conversion automatically, but unless you know your mailer is one of them, you may want to do the encoding manually.


The EDBIC character set is similar to (but less popular than) the ASCII character set in concept, but is significantly different in layout. It tends to be found only on old machines..
Emacs is both one of the most powerful and one of the most popular text editing programs in existence. Versions can be found for most platforms, and in fact multiple companies make versions, so for a given platform there might even be a choice. There is even a free GNU version available. The drawback with emacs is that it is not in the least bit lightweight. In fact, it goes so far in the other direction that even its advocates will occasionally joke about it. It is however extremely capable. Almost anything that one would need to relating to text can be done with emacs and is probably built-in. Even if one manages to find something that emacs was not built to do, emacs has a built-in Lisp interpreter capable of not only extending its text editing capabilities, but even of being used as a scripting language in its own right.
An embedded system is a computer that lives inside another device and acts as a component of that device. For example, current cars have an embedded computer under the hood that helps regulate much of their day to day operation.
An embedded file is a file that lives inside another and acts as a portion of that file. This is frequently seen with HTML files having embedded audio files; audio files often embedded in HTML include AU files, MIDI files, SID files, WAV files, AIFF files, and MOD files. Most browsers will ignore these files unless an appropriate plug-in is present.
An emulator is a program that allows one computer platform to mimic another for the purposes of running its software. Typically (but not always) running a program through an emulator will not be quite as pleasent an experience as running it on the real system.
A processor will be either "big endian" or "little endian" based upon the manner in which it encodes multiple byte values. There is no difference in performance between the two encoding methods, but it is one of the sources of difficulty when reading binary data on different platforms.
An environment (sometimes also called a runtime environment) is a collection of external variable items or parameters that a program can access when run. Information about the computer's hardware and the user can often be found in the environment.
EPOC is a lightweight OS. It is most commonly found on the Psion PDA.
Filename extensions originate back in the days of CP/M and basically allow a very rough grouping of different file types by putting a tag at the end of the name. To further complicate matters, the tag is sometimes separated by the name proper by a period "." and sometimes by a tab. While extensions are semi-enforced on CP/M, MS-DOS, and MS-Windows, they have no real meaning aside from convention on other platforms and are only optional.