Perhaps best known as being Vertigo's longest-running comic book series because of the fact that it began before Vertigo was a publisher, five years before in fact and that it's still ongoing. Apart from that, it is also known as the tale of John Constantine, one of Vertigo's most renown characters.
Unlike most Vertigo volumes, due to its extreme length, this one has had various writers, and oftentimes the series is judged within these writer's runs rather then as a whole since the series has changed through the decades.