Stands for "Moving Picture Experts Group." The MPEG organization, which works with the International Organization for Standardization (ISO), develops standards for digital audio and video compression. The group constantly works to develop more efficient ways to digitally compress and store audio and video files.
The term MPEG also refers to a type of multimedia file, which is denoted by the file extension ".mpg" or ".mpeg." These files are compressed movies that can contain both audio and video. Though they are compressed, MPEG files maintain most of the original quality of the uncompressed movie. This is why many videos on the Web, such as movie trailers and music videos, are available in the MPEG format.