Accessibility
The extent to which computers are easy to use and available to a wide range of users, including people with one or more physical disabilities.

Active Channel
A Web site that automatically delivers content to a user's computer on a regular schedule.

Active Desktop
An interface that integrates the Windows desktop with the Internet Explorer browsing software to provide a single metaphor for accessing content or applications.

Active Setup
An application that collects information about the user's computer before download of Internet Explorer begins, and then uses this information to manage the download intelligently.

ActiveX
An umbrella term for Microsoft technologies that enable developers to create interactive content for the World Wide Web. A set of language-independent interoperability technologies that enable software components written in different languages to work together in networked environments. The core technology elements of ActiveX are COM and DCOM.

Address class
A basis for differentiating networks of various sizes. The network class can be determined from the first octet of its IP address.

Address Resolution Protocol (ARP)
A protocol for determining a host's Ethernet address from its Internet address.

Advanced Configuration and Power Interface (ACPI)
A system interface that provides a standard way to control power management and Plug and Play functions of the computer hardware. ACPI allows the computer motherboard to describe its device configuration and power control hardware interface to Windows 98. This allows the operating system to automatically turn on and off standard devices, such as CD-ROMs, network cards, hard disk drives, and printers, as well as consumer devices connected to the computer, such as VCRs, TVs, phones, and stereos.

Advanced Power Management (APM)
A software interface (defined by Microsoft and Intel) between hardware-specific power management software (such as that located in a system BIOS) and an operating system power management driver.

ANSI
American National Standards Institute.

API
See application programming interface.

Applet
An HTML-based program built with Java that a browser temporarily downloads to a user's hard disk, from which location it runs when the Web page is open.

Application programming interface (API)
A set of routines that an application program uses to request and carry out lower-level services performed by the operating system.

Architecture
The structure of all or part of a computer system. Also refers to the design of system software.

ASPI
Advanced SCSI Programming Interface.

Asynchronous Transfer Mode (ATM)
A communications protocol defined for high-speed data communications.

Authenticode
A technology that makes it possible to identify who published a piece of software and verify that it has not been tampered with.