ID3v2 spec made easy

ID3v2 is a new tagging system that lets you put enriching and relevant information about your audio files within them. In more down to earth terms, ID3v2 is a chunk of data prepended to the binary audio data. Each ID3v2 tag holds one or more smaller chunks of information, called frames. These frames can contain any kind of information and data you could think of such as title, album, performer, website, lyrics, equalizer presets, pictures etc. The block scheme to the right is an example of how the layout of a typical ID3v2 tagged audio file may look like.
One of the design goals were that the ID3v2 should be very flexible and expandable. It is very easy to add new functions to the ID3v2 tag, because, just like in HTML, all parsers will ignore any information they don’t recognize. Since each frame can be 16MB and the entire tag can be 256MB you’ll probably never again be in the same situation as when you tried to write a useful comment in the old ID3 being limited to 30 characters.
Speaking of characters, the ID3v2 supports Unicode so even if you use the Bopomofo character set you’ll be able to write in your native language. You can also include in which language you’re writing so that one file might contain e.g. the same lyrics but in different languages.
Beyond cool.
Read ID3v2 made easy