Diamond Jigsaw Single Information and Ordering Links

[froopy seal]

Originally Posted by testudo

Another digital promo, this one has the vocal for The Invisible remix

http://www.discogs.com/Underworld-Di...elease/2983476

Forgive my ignorance, but what is a 'digital promo'? I mean, how do the compiling and distribution work? What does it make 'promo'?

P. S.: Having to ask about digital promos, but knowing what a vinyl is makes me feel old.