Access Provider
The company that provides you with Internet access and, in some cases, an online account on their computer system.

Acoustic Coupler
A type of modem which converts digital signals into sound for transmission through telephone lines, and performs the reverse operation when receiving such signals. Acoustic couplers generally have cups for the telephone handset.

Active Window
The top or front window in a multiple window environment.

A/D Converter
A device used to convert analog data to digital data. Analog data is continuously variable, while digital data contains discrete steps.

Additive Primaries
Red, green, and blue are the primary colors of light from which all other colors can be made.

Address Resolution
Conversion of an IP Address to the corresponding low-level physical address.

AIX
Advanced Interactive Executive - IBM's version of Unix.

Aliasing
Visibly jagged steps along angled or object edges, due to sharp tonal contrasts between pixels.

Analog
Continuously variable signals or data.

Anonymous Login Convention (FTP)
Standard username (anonymous) and password (guest) which allows login within FTP for the purpose of retrieving an unprotected file.

ANSI
American National Standards Institute. This organization is responsible for approving U.S. standards in many areas, including computers and communications. Standards approved by this organization are often called ANSI standards (e.g., ANSI C is the version of the C language approved by ANSI).

Application
Software that lets users do relatively complex tasks, as well as create and modify documents. Common application types include word processors, spreadsheets, database managers, and presentation graphics programs.

ARA
AppleTalk Remote Access. A protocol (and product) that provides system-level support for dial-in (modem) connections to an AppleTalk network. With ARA, you can call your desktop Mac from a PowerBook and remotely access all the available services - files, printers, servers, e-mail, etc.

Archie
An information system offering an electronic directory service for locating information in the Internet that is automatically updated. The best known use of archie is for scanning a database of the contents of more than 1000 Anonymous FTP sites around the world with more than 2,100,000 file names.

ARP
Address Resolution Protocol. Used to dynamically discover the low-level physical network hardware address that corresponds to the high level IP Address for a given host, for instance. ARP is limited to physical network systems that support broadcast packets that can be heard by all hosts on the network. See also Proxy ARP.

ARPANET
Advanced Research Projects Agency NETwork. A pioneering long-haul network funded by ARPA, an agency of the U.S. Department of Defense responsible for the development of new technology for the military. It served as the basis for early networking research as well as a central backbone during the development of the Internet. The ARPANET consisted of individual packet switching computers interconnected by leased lines.

ASCII
American (National) Standard Code for Information Interchange. A standard character-to-number encoding widely used in the computer industry.

Associate
Linking a document with the program that created it so that both can be opened with a single command.

AV
Audio-Visual. AV Macintosh models have video-capture hardware and have sophisticated sound (and video) recording capabilities.

AU sounds
A type of audio format used in the World Wide Web.