ID3 tag

ID3 tag

Meta-data for MP3 and MP3pro audio files that describe their contents, including song title, artist, album, year, comment, CD track and genre. ID3 tags are used for searching as well as displaying the title being played. In many cases, ID3 tags are not filled in or are erroneous, and an ID3 "tagger" utility can be used to edit them.

Why Not on the Original CDs?
Not having meta-data built into the original audio CD format was an extreme lack of vision. As engineers were developing CD technology in the late 1970s, the display circuits were too costly to show this information on most CD players. However, it would have been relatively simple to reserve a few thousand out of the 650 million bytes on the disc to store this obvious data for future use. See online music database.

ID3 Format
Residing at the end of the audio file, the original ID3 tag was limited to 128 bytes, comprising 30-byte text fields, a 4-byte year and a 1-byte genre (up to 80 categories). Version 1.1 (ID3v1.1) added the CD track number; however, Version 2 (ID3v2) was a major departure.

ID3v2 supports variable-length fields with ample capacity to include titles of any length as well as the album cover image. The meta-data was switched to the beginning of the file so that song information can be displayed at the start for streaming audio. For more information, visit www.id3.org. See metadata.