Michael Bland
Media playback is unsupported on your device
Video

Why is so much music in Prince's vault?

The musician Prince keeps a stash of unreleased music inside a secure vault in the basement of his recording studio in Minneapolis.

Nobody is quite sure how much music is inside - but estimates vary between 500 and 2,000 finished tracks.

But why does he have so much material?

People who have worked closely with him says he is constantly recording new music, even when he goes on tour.

Go to next video: 'I started Prince's vault'