MP3

"An MPEG-1 Audio Layer 3 (commonly known as "MP3") is the most popular digital audio compression algorithm in use on the Internet, and the compression it provides makes an audio file 'smaller' by a factor of 12 to one withou significantly reducing sound quality." Recording Indsutry Association of America, et al. v. Diamond Multimedia Systems, Inc., 180 F.3d 1072, 1074 (1999).