.m4a File — MPEG-4 Audio

M4A is an audio-only file extension for the MPEG-4 container format, typically containing audio encoded with the AAC codec, though it can also contain Apple Lossless (ALAC) audio. Apple adopted M4A as the standard file extension for audio purchased from the iTunes Store and ripped from CDs using iTunes. The distinction between .m4a and .mp4 is purely about intent — .m4a signals an audio-only file to applications, while .mp4 may contain video. M4A files support rich metadata including title, artist, album, track number, genre, album art, lyrics, and Apple-specific fields like ratings and play counts. Files with DRM protection use the .m4p extension instead. M4A with AAC encoding provides superior audio quality compared to MP3 at equivalent bitrates, while M4A with ALAC provides lossless audio compression. The format is natively supported by iTunes, Apple Music, iPhone, iPad, macOS, and QuickTime, with broad support in third-party players. M4A has become one of the most common audio formats due to Apple's market influence and AAC's inclusion in various international standards.