vv221: World of Darkness is the PnP setting that served as a base for Vampire: The Masquerade - Bloodlines.
Well, actually I think it is quite a bit more than that, but I’ll let the experts explain this better than me ;)
World of Darkness (WoD) is the universe that the Vampire: The Requiem, Werewolf: The Forsaken, and Mage: The Awakening PnP RPGs take place in. The old WoD (prior to 2003) included Vampire: The Masquerade (the basis for Bloodlines), Werewolf: The Apocalypse, Mage: The Ascension, Wraith: The Oblivion, Hunter: The Reckoning and quite a few other spinoff games, none of which are still published.