File type: Audio Files
M4A files are audio files that use the MPEG-4 compression algorithm for compressing audio. It essentially uses a similar compression algorithm to that used for encoding a .MP4 video.
It only excludes any video data. MPEG-4 audio files may also include copyright protection in order to prevent piracy and unlawful distribution of files.
For example the audio files sold from the iTunes Music Store are copy protected in the same manner and usually have M4P format.
The files which are in .M4A format comprise of the audio layer or non-video part of MPEG 4 movies only. M4A has been widely accepted as a new standard compressing audio.
This format is also called Apple Lossless format or Apple Lossless Encoder format or even ALE shortly.
It is a relatively new codec that has been designed specifically to provide complete lossless encoding to ensure that even though high compression is achieved there is no loss of actual audio information and hence can use less storage space.