'''Halo numbers''' are the numbers assigned to pieces of the [[Nine Inch Nails]] discography in the order that they are released, so that a collection can be neatly ordered, supplied, and bragged about. Halo numbers are sometimes modified for variations of a release, such as the different versions of ''The Downward Spiral''.
Some Halo numbers are shared with promotional items; Halo 10 is shared with the ''Hurt'' and ''Piggy'' promo CDs and Halo 16 is shared with the ''Into The Void'' promo CD. There are also promotional releases that are given 'Seed' numbers.