freeb is a database of compact disc track listings, where all the content is under the GNU General Public License. It was originally based on the now-proprietary CDDB (compact disc database). As of April 24, 2006, the database holds just under 2,000,000 CDs. To look up CD information over the Internet, a client program calculates a nearly unique disc ID and then queries the database. If the disc is in the database, the client is able to retrieve and display the artist, album title, tracklist and some additional information.