Like I said- it is a big part of the scene- however one does not have to use drugs and be a raver.
"Part III: Drugs
Drugs. The big ‘D’ word. Drugs have been a part of the rave scene since the beginning. Yes, it is possible to go to a rave and not do drugs. Yes, it is possible to be a raver and live a drug-free lifestyle. No, a rave is not dependent on drug use. Nevertheless, one cannot separate the scene from the drug use. It is impossible. Anyone that says otherwise is a liar.
In England, the rave scene originated with MDMA or Ecstasy. In America, it was LSD or acid. It was common to see blotter art on flyers. Raves were named Dose or Acid Test. Raves are ways of changing the psychological state of a human being bringing them into a different plane of existence. This goes hand-in-hand with psychedelic drugs.
At first, acid and occasional marijuana use were the only drugs seen at raves in America. Then, Ecstasy moved in. It became the raver drug of choice. Ecstasy broke down barriers of communication. It enhanced pleasure and sensation. Music became physically pleasurable. Strangers became people to be loved. Ecstasy broke down egos. It was a perfect fit with the happy family that the rave scene was trying to create.
Today, Ecstasy is still popular, and acid is still used by a sizable minority. However, as greed has taken hold within the scene, Ecstasy is no longer pure. It is usually cut with baking powder, or worse, various pesticides and poisons. Nitrous Oxide has become popular. Within the last year or so, hard drugs have moved into the scene, crystal meth, heroin, and even alcohol.
Drugs are a frequent topic of debate among ravers. Some think that drugs should be done away with entirely. Others think that only drugs that increase the vibe should be allowed, namely marijuana, LSD, and ecstasy. Still others think that the rave scene is about personal choice and determining which drugs are good and which drugs are bad is imposing personal morals on others. The fact of the matter is, as the rave scene is appropriated (which I will examine later) into mainstream society, fewer people are concerned about the vibe, and more concerned about being wasted. This is where the ketamine, the meth, and the heroin come in."
Taken straight from here: http://www.phantasmagoria.f2s.com/writings/raveindex.html