Ogg

Being a Container format, ogg can embed third-party codecs (such as DivX, Dirac, XviD, mp3 and others) but usually Ogg is used with the following.

• Audio codecs

*lossy
 *Speex handles voice data at low bitrates (~8-32 kbit/s/channel)
 *Vorbis handles general audio data at mid- to high-level bitrates (~16-256 kbit/s/channel)
*lossless
 *FLAC handles archival and high fidelity audio data

• Text codec

*Writ a text codec designed to embed subtitles or captions

• Video codecs

*Theora based upon On2's VP3, it is targeted at competing with MPEG-4 video (i.e. DivX and XviD), RealVideo, or Windows Media Video.
*Tarkin an experimental codec utilizing 3D wavelet transforms. It has been put on hold, with Theora becoming the main focus for video encoding.

(Taken from the wikipedia article)