Digital audio compression and playback standard able to fit 150 songs requiring 7.5 gigabytes or more of storage space on a single CD with very little loss in sound quality. Compression can reduce a file size to 1/20th or even less of its original size. MP3 files can be played on a computer, or electronic players with no moving parts. MP3 is by far the most popular software of its kind and is downloadable free from numerous websites. Developed under the sponsorship of Motion Pictures Experts Group.