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	Algorithm
	Any step-by-step problem-solving procedure. Transmission of compressed video over a communications network requires sophisticated compression algorithms. Some videoconferencing systems offer both proprietary and standard compression algorithms.
	Analogue Signal
	A type of signal that encodes voice, video, or data transmitted over wire or through the air, and is commonly represented as an oscillating wave. An analogue signal can take any value in a range and changes smoothly between values, as opposed to digital signals, which is characterized by discrete bits of information in numerical steps. An analogue signal can transmit analogue or digital data.
	ADC (Analogue-to-Digital Conversion)
	Process of converting analogue signals to a digital representation. DAC represents the reverse translation.
	ATM (Asynchronous Transfer Mode)
	A high bandwidth, High speed (up to 155 Mbps), controlled-delay fixed-size packet switching and transmission system integrating multiple data types (voice, video, and data). Uses fixed-size packets also known as "cells" (ATM is often referred to as "cell relay").
	Asynchronous Transmission
	A mode in which the sending and receiving serial hosts know where a character begins and ends because each byte is framed with additional bits, called a start bit and a stop bit. A start bit indicates the beginning of a new character; it is always 0 (zero). A stop bit marks the end of the character. The time interval between characters may be of varying lengths. Synchronous data uses an external reference clock to unify both ends of the data circuit.
	Audio
	In video communications, electrical signals that carry sounds. The term is also used to describe systems concerned with sound with recording and transmission; speech pickup systems, transmission links that carry sounds, amplifiers and the like.
	Autonomous System
	Internet (TCP/IP) terminology for a collection of gateways (routers) that fall under one administrative entity and cooperate using a common Interior Gateway Protocol (IGP).