AIFF is an abbrevitaion for Audio Interchange File Format and an audio format created for storing high-quality audio data for computers and electronic devices.
Mainly used on the Macintosh platform, AIFF is an uncompressed and lossless format, that provides support for streaming several audio tracks from one's Mac to an app.
AIFF audio files can be currently played using most audio players. AIFF players will usually allow their users to build their own playlists that contain tracks of other formats, besides the AIFF ones.