Ravers are a faction within the state of Florida. They've gain control of the hallucinogen market in Vice City which gives them much power and can pretty much orchestrate like a gang.
Since the early 1990's, the ravers have taken control of a warehouse in Vice City. The building has been dubbed Gabber Airwaves. Over time, their numbers grew which lead to a hidden hierarchy of sorts. Bill Farber is elected as the leader in early 2009 due his strange disappearance shortly before. Bill gained control of all hierarchical parts of the of the rave scene. The ravers have never been more powerful.
Demise of 2010
Bill's poor business decisions eventually lead to his death in 2010. As the leader, Bill decided to start selling hallucinogens to the Vacilli crime family. The deal went perfectly until it was ambushed by Rick Chance. He knew that if he went after Rick it would only hurt his faction, so he let the Vacilli's deal with him. It didn't work. At all. Rick managed to push back the Vacilli's with the help of Niko Bellic. He was killed by Niko and Rick due to his actions. The loss of another lead shook the ravers from there on out. They had lost large numbers of their people defending their drugs and their leader all for nothing. All hallucinogen supply went right into the pockets of Niko and Rick.
Life after 2010
Without a proper leader let alone a hierarchy, the ravers went make to their typical lifestyle of getting high and partying. Their numbers were smaller and it didn't feel as good before. Eventually, over time, the ravers either mature and move on or overdose.