In comic books, an intercompany crossover (also called cross-company or company crossover) is a comic or series of comics where characters that at the time of publication are the property of one company meet those owned by another company (for example, DC Comics' Superman meeting Marvel's Spider-Man, DC's Wonder Woman meeting Marvel's Storm, or DC's Batman meeting Marvel's Wolverine). These usually occur in "one-shot" issues or miniseries.
Some crossovers are part of canon. But most are outside of the continuity of a character's regular title or series of stories. They can be a joke, a gag, a dream sequence, or even a "what if" scenario (such as DC's Elseworlds).
Amalgam Comics was a collaborative publishing imprint shared by DC Comics and Marvel Comics, in which the two comic book publishers merged their characters into new ones (e.g., DC Comics' Batman and Marvel Comics' Wolverine become the Amalgam Comics character Dark Claw). These characters first appeared in a series of 12 comic books which were published in April 1996, between Marvel vs. DC #3 and DC vs. Marvel #4, the last two issues of the DC vs. Marvel crossover event. A second set of 12 comic books followed one year later in June 1997, but without the crossover event as a background. All 24 of these issues occurred between the aforementioned issues of DC vs. Marvel.
The Official Handbook of the Marvel Universe: Alternate Universes 2005 designated the Amalgam Universe as Earth-9602 in the Marvel Multiverse. DC Comics has not yet identified or numbered the Amalgam Universe in its Multiverse.