Entagged is an Open-source audiofile tagger.
A tag is a piece of information stored inside the audio file that contains the title, artist, track number, and other data relative to that file. Entagged provides a convenient way of changing the value of tag fields, either manually, or automatically via the freedb database. The freedb database is a server containing information about CDs (album or compilation) to which you can connect, and obtain data necessary to correctly tag your audio files.