Ever wonder how your computer knows the song titles when you insert an audio CD? The answer is more complicated than you might think. Ideally, that information would be written onto the disc itself, but the creators of the CD format weren’t so forward-thinking. CD-Text, a later development, does just that, but few players can read it (nonetheless, I still encode it on every disc I master).

Usually, the information comes from CDDB (short for Compact Disc DataBase), owned by a company called Gracenote. When iTunes or another compatible software application sees you’ve inserted an audio CD, it uses the durations of the tracks as a “fingerprint” to calculate a proprietary disc ID. It then queries CDDB with that ID to receive the artist name, CD title, and track list.