Song rhythm tracks
Musicians would also use these backing tracks to practice, which was mentioned before. Guitarists would find what key the track is being played in, and play over it using either the major or minor scale to solo along, or to just jam. Vocalists would use these to practice their pitch, and their free-style. Not only would one person play along with a track, but a few people could join in. If they are lucky, they may just come up with a killer song.