Gracenote

From Wikipedia: Gracenote is a commercial enterprise which maintains and licenses a database containing information about the contents of audio CDs. The database is accessible online over the Internet. Computer software applications such as iTunes that are capable of playing CDs use Gracenote’s CDDB or similar commercial services such as All Media Guide’s AMG LASSO and MusicIP, or open-source projects such as freedb and MusicBrainz. These programs generally offer the option of contributing track listings, and most of the track listings in the Gracenote database are voluntary contributions by individual users of CD-player software.

Additionally, Gracenote operates a digital file identification service which allows digital music files to be identified. As well as a media management service for media management such as the generation of playlists, and recommendation of music.

Gracenote’s database is mainly created via the contributions of its many users. If the music is not available in the Gracenote database, the service requests the user to input information such as the artist, album, and song names related to the music. Gracenote also receives some music information from third pary database companies and record labels.