DVD'S and main menus

i have this site that i download dvd movies some of the files are in vob format so are rared down and a tar file witch i am to saw wot that file is but with the vob ans tar files thier are IDX file and a SUB file wot are they can any one tell me.

many thanx

The SUB files are Subtitle files and can be turned on or off during playback with some AVI Players. They can also be included in a DVD2SVCD conversion of the AVI to VCD/SVCD or DVDR to add subtitles as well.