Vertigo started as the "adult" imprint of DC Comics, publishing their in-universe titles of Animal Man, Doom Patrol, Swamp Thing, Hellblazer, Black Orchid, Sandman, and others. However, it eventually evolved into a creator-owned imprint, for stories outside of the DC universe. Its adult roots have allowed for more mature themes and more trans and intersex characters than the "normal" DC.
Over time, DC began to integrate the elements of Vertigo that took place in the DC Universe back into their main line as they moved the imprint towards the creator-owned status. This effectively was finalized with DC's 2011 reboot, when the long-standing Vertigo character of John Constantine was fully integrated into the main DC line by starring in Justice League Dark.