M4A (MPEG-4 Audio) is a filename extension used to represent audio files encoded with Advanced Audio Coding (AAC) or Apple Lossless Audio Codec (ALAC). AAC is a lossy compression method, meaning some audio data is discarded during encoding to reduce file size. ALAC, on the other hand, is a lossless compression method, preserving all original audio data, resulting in larger file sizes but higher fidelity. M4A files are commonly used for storing songs, podcasts, audiobooks, and other audio content. They are often associated with Apple's iTunes and iOS devices, but the format is widely supported across various platforms and media players. Compared to the older MP3 format, AAC generally offers better audio quality at the same bitrate or similar quality at a lower bitrate. M4A files can also contain metadata such as song title, artist, album, and artwork. The format is a part of the MPEG-4 Part 14 standard, which specifies the container format for multimedia content.