When a Sun Microsystems or other Unix computer makes a noise, it does so in AU file format. And because the Internet is dominated by Unix boxes, you'll find a lot of AU files there. Luckily, Macintosh and PC browsers such as Netscape Navigator are usually able to play AU files, which have the extension .au. A sound file that originated on a PC is likely to be in WAV or MIDI format instead.

in essence, a measure of how many bits describes each sound in an audio file. A low bit rate means lower quality and a smaller file size, while a high bit rate means better quality and larger files. The standard bit rate is 128 kbps.

The process by which streaming audio and video saves data in advance of playing it. Programs such as RealPlayer or Windows Media Player will download a part of the video or audio stream before starting to play, then continue the downloading as the stream plays. If the playing catches up to the end of the buffer, the stream will pause while further buffering occurs.

A centralized database on the Web that can recognize most CDs and send track listings to your audio player so that you don't have to type in all the information yourself.

A small cassette that records and plays back audio digitally, at CD quality and better.