Among the lossy formats, those based on MPEG standards are the most popular. MPEG is a suite of open standards for compressed audio and video developed by the Motion Picture Experts Group, a working group established in 1988 under the direction of the International Standards Organization.
MPEG's standards have been released in families, each designated by number. MPEG-1 (approved in 1992), supports video encoding as well as mono and stereo audio encoding at three sampling rates; MPEG-2 (1994) increases the number of sampling rates and provides for broadcast-quality video and surround sound; MPEG-4 (1998) supports a broad range of multimedia and is able to integrate synthetic audio systems (such as MIDI and text-to-speech programs); MPEG-7 (2001) provides tools for managing metadata.3.12
Of the many formats provided by the MPEG standards, the most common are MP3 and AAC.