Glossary of Internet Terms

Letter A

©2006 by Walt Howe
(last updated 22 October 2012)


Select the first character of the term you want to look up or use the Search link at the right.

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This Internet Glossary is growing. Terms and definitions are being added all the time. If you have comments, corrections, or suggested additions, please send them to Walt Howe using the form at the end of the Glossary. My thanks for the many suggestions that already have been included.


Web Developers! See how to link to terms in the glossary from your web page.

A

acceptable use policy (AUP)
A definition of content and uses permitted on a site or network as conditions of using that site or network. AUP are often stated for ISPs, networks, organizations, and universities.
ADSL
Asymmetric Digital Subscriber Line. Technology to carry high speed data over ordinary phone lines. It is up to 70 times as fast as a 28.8 modem, and can be used concurrently with voice over the same line. It is gradually being offered to homes commercially now. It is called "asymmetric" because download speeds to the subscriber are faster than upload speeds from the subscriber. See DSL.
adware
Any software which serves banner ads or pop-up ads to you while in use. It is sometimes installed in freeware or shareware which you download from the nets, and provides one more channel for advertisers to reach you. Some adware will also track your files, net usage, and software and report it back to advertisers to help them channel relevant ads to you. See spyware.
afk
Chat abbreviation for "away from keyboard".
ahnentafel
If you run into this term, you must be dealing with Genealogy, a rich field for exploration on the nets. Ahnentafel is a German word meaning "ancestor table." It refers to a system of numbering the ancestors of a person. See What is Ahnentafel?.
AIFF
Audio Interchange File Format. A common audio file format originally for Macs, but used with other systems, too. See the Audio Guide and the File Extension Guide for more information.
aliasing, anti-aliasing
Pictures on your computer monitor are made up of square pixels. When the edge of a solid colored object in a GIF image is a diagonal or curved line, and it is displayed against a contrasting color, the edges appear jagged, like stair steps. This jagged appearance is called aliasing. The jagged appearance can be softened by filling in adjacent pixels with intermediate colors between the object and the background. This softening of the edges is called anti-aliasing. Software like PhotoShop can apply anti-aliasing for you automatically. It is often the default setting.

One problem with anti-aliasing GIF images is that it increases the number of colors used, necessarily increasing the file size. You must decide whether quick loading or smoothed edges serves your needs better.

A second problem can occur when you create transparent GIFs. If the edges are anti-aliased against a different color background than the background it will be displayed against, the intermediate color pixels will be the wrong color and a halo effect occurs around the image. Make sure that when you anti-alias transparent GIFs, that you do it against the transparency or the final background color. If you are using a tiled background image where the background color changes, you must anti-aias against a transparent background. Feathering is a similar technique of putting partially transparent pixels around the edge to soften the aliasing.


Aliased,
magnified
5 times

Anti-aliased,
Magnified
5 times
Transparent
anti-aliased
against
wrong
background
alpha test
In software development, an early stage of testing by in-house personnel to identify bugs in the program. It usually involves systematically trying out all of a program's functions. Compare with beta test.
animated GIF
A GIF graphic file, which consists of two or more images shown in a timed sequence to give the effect of motion.
anonymous ftp
A traditional form of login to a public ftp site where the username is given as 'anonymous' and the password is your e-mail address, for example 'walthowe@delphiforums.com'. See .
anti-aliasing
See aliasing.
API
Application Program Interface. An interface between the operating system and application programs that specifies how the two communicate with each other.
applet
An application that is downloaded from a web page and executed by browser software. Also, an HTML tag that defines an applet program.
archie
One of the first search engines introduced to the nets, developed by Peter Deutsch and others at McGill U. Archie is software that indexes thousands of ftp sites and lets you search for the files and software that you want. It was short for "archiver", protested Deutsch, after the search tools VERONICA and JUGhead followed it.
See History.
archive
1. A storage repository for software, data, or other materials to be saved and preserved.
2. A technique of combining multiple files into a single file to enable easier backup, handling or transmission. Some of the software programs used to archive files are PKZIP, WinZip, Stuffit, and tar. Files with the following extensions are likely to be archived: sea, tar, taz, taZ, tgz, and zip. See compression.
ARPANET
The network created by the Advanced Research Projects Agency (ARPA) that became the Internet. See the Internet History
.art
A graphics format used on AOL. Plug-ins are available for non-AOL browsers to view graphics with a .art extension.
ASCII
American Standard Code for Information Interchange. A standard way to encode upper and lower case letters in the English alphabet, numbers, and special characters using only seven bits, and therefore limited to 128 characters. The basis for coding simple text files. ASCII Table. To provide more characters, such as accented characters and mathematical symbols, an 8th bit is often added, providing 256 characters in all. There are different standard 256 character sets, but the most common is ISO Latin 1 (ISO 8859-1) used on the web.
ASCII art
Artwork composed entirely of ASCII characters used as lines and shapes, not as characters with meanings. The simplest ASCII art is the simple smiley faces, but at the other end of the scale, they can be large, elaborate pictures. For a good collection of ASCII art, see the ASCII Dictionary
ASCII file
ASCII files are those that only use the 128 characters that can be encoded with 7 binary digits. This means that most text files are ASCII files. Word processed files, which include special characters and control codes are usually encoded with 8 binary digits. Some Internet protocols only support 7-bit text, such as simple mailers and newsgroups. Because of this, ways have been developed to encode binary files into ASCII form. The most common of these are uuencode and binhex, the latter for Macintosh files, primarily. Two more examples of 7-bit file systems are postscript(.ps files) and TeX (.tex files), which are word processing systems that allow encoding of complex information in 7-bit form. Common extensions for ASCII files are .txt, .uue, .xxe, .hqx, .ps, and .tex. Also files with names like README or index are almost always text files. The .doc extension may be text or may be 8-bit, and you need to know
a/s/l
A coded question frequently used in teenage chats. When you see someone type a/s/l?, they are asking for your age, sex, and location. Use your judgment whether to respond or not.
ASP
1. Active Server Pages
2. Application Service Provider
ATM
Asynchronous Transfer Mode. A packet switching model for fast long distance communications that uses fixed packet size and allows for intelligent decisions on routing, handling, prioritization, and costing. This allows for special handling and routing for data that must be reassembled quickly and accurately, such as live Video. See differentiated service.
avatar
Here are three progressive meanings for 'avatar' to show you where it came from and where it is today:Author's VZones avatar
  1. A Hindu incarnation on Earth of a god.
  2. In unix, a superuser--equal in privileges to root.
  3. In chat and in games, an icon to represent a participant. For an excellent example of automated, customizable avatars in chat in a virtual world setting, see VZones. The author's avatar is at the right. Try it!
AVI
Audio Video Interleaved. A Microsoft video format where audio and video coding appears in alternate segments. AVI files will end with an .avi extension.

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For Web Developers: How to Link to the glossary terms.
You can link to any term in this glossary with a link in this form:

http://www.walthowe.com/glossary/*.html#term

Replace the asterisk in *.html with the first letter of the term you are linking to. Terms with more than one word will generally use an underline to link the words.