Core Audio Format

The Core Audio Format (.caf) is a container for storing audio, developed by Apple Inc. It is compatible with Mac OS X 10.4 and higher; Mac OS X 10.3 needs QuickTime 7 to be installed.

Core Audio Format (.caf) is designed to overcome limitations of older digital audio formats, including AIFF and WAV. Just like the QuickTime  container, a   container can contain many different audio formats, metadata tracks, and much more data. Like the RF64, it is not limited to a 4 GB file size and a single  file can theoretically save hundreds of years of recorded audio due to its use of 64-bit file offsets.

GarageBand, Soundtrack Pro, and Logic Studio use the  format for their loop and sound effects library, particularly for surround-sound audio compressed with the Apple Lossless (ALAC) codec. It is also what is used to send Audio Messages over iMessage on iOS and Mac OS.