(1) In networking, an individual piece of information sent on a network. (2) In Core Audio, an encoding-defined unit of audio data comprising one or more frames. For PCM audio, each packet corresponds to one frame. For compressed audio, each packet corresponds to an encoding-defined number of uncompressed frames. For example, one packet of MPEG-2 AAC data decompresses to 1,024 frames of PCM data. Compare webpage template, uniquing.