Like MP3, Advanced Audio Coding is an audio encoding scheme specified by the MPEG-2 standard. Although it is part of MPEG-2 standard, it is not compatible with the MPEG Layer scheme or MP3. AAC was design by researchers from a number of companies and can be licensed from Dolby Laboratories. AAC encoding is more efficient than MP3, resulting in smaller file sizes for audio of similar quality. AAC can also provide many more audio channels than MP3, as well as a wider range of sampling rates for better sound quality than is possible with MP3. Although AAC by itself has not yet been widely used, it has been used as the basis for several proprietary secure formats, and it will be used in the audio portion of the MPEG-4 standard.

This definition is in context to Computer Technology. See more contextual defintions for AAC (Advanced Audio Coding).