MP3

MP3 is slang for "MPEG Layer-3". MPEG stands for "Moving Picture Experts Group," and refers to the experts who developed MPEG - a set of industry standards for digitally encoding video and audio information.
The file extension for the audio layer (layer 3) of a MPEG file is MP3. This layer uses perceptual (what can be heard) audio coding and psychoacoustic compression to remove redundant or irrelevant sound signals. A popular audio compression standard for Internet delivery of sound files.