CDDB and FreeDB are online databases holding audio CD details. CDDB and FreeDB enabled software will allow you to download CD information such as track, artist, title, etc. when your CD is loaded and you are connected to the Internet. Paticularly useful if you're ripping a CD as all the information will automatically be intered into the ID3 tags. The main difference between the two is that CDDB is commercial and FreeDB isn't so developers don't have to pay a license to add FreeDB to their products.