ID3tags

ID3 tags are metadata containers embedded in MP3 audio files that store information about the recording, such as title, artist, album, year, genre, track number, and comments. They enable music players and library software to display track information without analyzing the audio data.

There are two major generations of ID3 tags: ID3v1 and ID3v2. ID3v1 was introduced in the early days of MP3 and is stored as a 128-byte block at the end of the file. It has a fixed layout with fields for title, artist, album, year, a 30-character comment, and a genre byte, offering only a small amount of information.

ID3v2 is the more flexible and widely used standard. It places a tag header at the beginning of the file and follows it with one or more frames that carry individual pieces of metadata. Common frame IDs include TIT2 for the title, TPE1 for the lead artist, TALB for the album, TYER or TDRC for the year or recording time, TRCK for the track number, TCON for the genre, and COMM for comments. ID3v2 supports Unicode text, longer descriptions, embedded artwork, and extensive custom fields. It has multiple versions, notably ID3v2.2, ID3v2.3, and ID3v2.4, each with different frame sets and rules.

The tag header in ID3v2 specifies the version and size, and the frames themselves carry their own data, with encoding and size fields. Some software may ignore unknown frames or handle them differently, and there can be compatibility issues when moving files between players that support different ID3v2 versions.

ID3 tags are widely used in MP3 files to enable automatic display and organization of music libraries. While ID3v1 tags persist for legacy compatibility, modern tagging tends to rely on ID3v2 for richer metadata and compatibility with contemporary players and tagging software.