A field of metadata in MP3 and MP3pro audio files. The tags describe the 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, also called an "audio tagger" or "MP3 tagger," can be used to update them. See
audio tagging.
Other than MP3
Although often erroneously called ID3 tags, other audio files (AAC, WMA, Ogg Vorbis, etc.) have their own metadata tag format that holds the same kinds of data. See
music search and
MusicBrainz.
Why Were Song Titles Missing?
CDs followed phonograph records, which contained nothing but sound waves "carved" into the vinyl platters. Reserving a few thousand bytes for the names of the album, artist and songs when there were 650 million available on the disc might seem obvious, but nobody envisioned playing music on the computer, and digital displays on CD players were expensive back then. Therefore, track number and length were the only metadata in a CD until more descriptive fields (tags) were added later (see
CD Text).
ID3 Format
Version 2 of ID3 (ID3v2) supports the album cover image as well as unlimited title length. The tags were moved to the beginning of the file so that song information is displayed at the start for streaming audio. Version 1 was limited to 30-byte text fields in the last 128 bytes of the file, a 4-byte year and 1-byte genre (80 categories). Version 1.1 (ID3v1.1) added CD track number. See
music CD identification,
music search,
metadata and
audio streaming.