ID3 is a very popular audio file data tagging format thas is actively used by software and hardware developers around the world. ID3 tags are supported in software such as [http://itunes.com iTunes], Windows Media Player, WinAmp, YME, MusicMatch and hardware players like the Ipod, Creative Zen, Toshiba Gigabeat and Sony Walkman.
An ID3 tag is data in an MP3 audio file stored in a prescribed format. This data commonly contains the Artist name, Song title, Year and Genre of the current audio file. This website contains the standards information for the various ID3 tagging formats.