Can Some1 explain me what are vobs ifo and bup files??

[Kinger]

I mean what each file does
y does the ifo files are neccecary???
and bla bla bla....
thx...

[setarip]

VOB - Contains ALL of the actual video and audio

IFO - InFOrmation - Contains navigational information (Video and audio formats, subtitle formats, chapter points, layer breaks, timing, etc.) needed for playback

BUP - BackUP - A duplicate of the IFO file