MPEG-4 (or MPEG4) is a standard format storing compressed video data in a file. The specification is governed by the MPEG group.

The evolution of the MPEG-4 standard is a bit complex. Briefly, the MPEG group adopted MPEG-4 as the standard for delivering multimedia content over low bandwidth connections like the Internet. The MPEG-4 specification was designed to allow the protocol itself to evolve and each iteration is called a version or part. The versions are distinguished by a profile included at the beginning of the file. Currently the MPEG-4 protocol in largest usage is version 2 (i.e. MPEG-4 Version 2), not to be confused with MPEG-2 the compression standard used in DVDs and for satellite/cable digital broadcasts. Fun huh?

The ITU also specifies video compression formats and MPEG-4 (Visual) is also known as ITU-T H.263 or H.263 for short.

H.263 (MPEG-4) is a useful standard that has been widely adopted in video surveillance. However, it has its limitations and many vendors have invented compression techniques that do a better job. The public standards are also advancing and have converged on a new standard called H.264 or MPEG-4 (part 10). In an effort to end the confusion (or perhaps add to it) the ITU and MPEG groups have reached a consensus to call the new standard Advanced Video Coding (AVC).