MP3 is a format standard for music file compression. It was codified by the Motion Picture Experts Group, a working group of the International Organization for Standardization (ISO). It compresses audio CD data to approximately 1/12 its original size. Because the MP3 encoding algorithm has been made publicly available, there are various encoders and decoders that are compliant with this standard.
NOTE: MP3 is an acronym for MPEG-1 audio layer 3.