Marvel Comics itself exists as a company within the Marvel Universe, and versions of people such as Stan Lee and Jack Kirby have appeared in some of the stories, whereas characters like Steve Rogers, (Captain America's alter ego), have worked for Marvel. The Marvel of this reality publishes comics that adapt the actual adventures of the superheroes (except for details not known to the public, like their secret identities); many of these are licensed with the permission of the heroes themselves, who customarily donate their share of profits to charity. Additionally, the DC Comics Universe is also said to exist in the Marvel Universe as one of the many alternative universes. The reverse may also be said concerning the DC Universe. This is one method of explaining the various crossover stories co-published by the two companies.