What is .M4A?

.m4a file extensions are audio files that are compressed with using a lossless codec meaning that there is no loss in quality of the file. These are then saved in the MPEG-4 container but stores audio instead of video.

What programs play .M4A?

Any of the following programs to open .m4a files:

Apple iTunes
Apple QuickTime Player
Microsoft Windows Media Player
Media Player Classic
KSP Sound Player
Roxio Creator 2010
Nullsoft Winamp Media Player
NCH Swift Sound WavePad