A file with a .aac extension is an audio file. Although .aac files are common, the MP4 container is also commonly used for AAC audio. AAC audio is used with the iTunes music store and supported by all of Apple's iPod models. It is also supported by several other consumer electronics products including Sony's PlayStation Portable (PSP), PlayStation 3 and Microsoft's Xbox 360.
AAC is intended to be a replacement for the MP3 audio format. It provides higher audio quality at comparable bitrate.
