APE is a file extension used for Monkey's Audio files. This is a lossless compression format for audio data.
Data file compression is employed in order to file size for audio files. This will reduce bandwidth, file transfer time, and/or storage requirements. A digital recording (such as a CD) encoded to the Monkey's Audio format can be decompressed into an identical copy of the original audio data. As with the FLAC and Apple Lossless format, files encoded to Monkey's Audio are typically reduced to about half of the original size, with data transfer rates and bandwidth requirements being reduced accordingly. Monkey's Audio's advantages are slightly superior compression rates compared to FLAC as well as multithreading/multicore support.
Monkey's Audio main drawbacks are the fact that it employs a symmetric algorithm, meaning the decoding takes comparable resources to encoding, which makes it unsuitable for all but the fastest portable players.
The extension .apl is used for track metadata.