AIFF (Audio Interchange File Format) is a file format used by Macintosh computers and Silicon Graphics Incorporated to store and transmit high-quality audio data such as music. It can store monaural, stereo or multi-channel sound as used for soundtracks. Apple Computer developed the AIFF format in 1987-88 in accordance with Electronic Arts Interchange File Format (IFF) standards. For this reason, AIFF files might have the extension .aif or .ief.

AIFF files are uncompressed, making the files quite large compared to the ubiquitous MP3 format. AIFF files are comparable to Microsoft's wave files, because they are high quality they are excellent for burning to CD. A hybrid variety of AIFF, termed AIFF-C, supports compression algorithms to the tune of 6:1. Compressed audio files do not have the same full quality of uncompressed files, though the difference will be less noticeable on small portable audio devices such as MP3 players.

The structure of an AIFF file contains distinct blocks of data called "chunks." Each chunk contains specific information about the file's contents. For example, a file will have a common chunk, a sound data chunk and a chunk ID. Other chunks include a name, author and copyright chunk. Perhaps owing in part to this structure, AIFF files have been commonly used in professional recording industries for many years.

Though the AIFF file was designed for Macintosh computers, the format can be read by PCs as well, just as wave files can be read by Macintosh computers. Standardization of protocols and interoperability among manufacturers in conjunction with groups like the IFF has made cross-platform compatibility possible. AIFF files are mainly used as an interchange format, either to capture live recordings or to copy existing recordings in order to transfer the sound data to another format, such as burning to disk. Though AIFF files are popular among Macintosh users and audio professionals, PC users tend to use wave files instead.