A scam, or a confidence trick, is an attempt to defraud a person or group after first gaining their trust. Confidence tricks exploit victims using a combination of the victim's credulity, naïveté, compassion, vanity, confidence, irresponsibility, and greed. Researchers have defined confidence tricks as "a distinctive species of fraudulent conduct ... intending to further voluntary exchanges that are not mutually beneficial", as they "benefit con operators at the expense of their victims ". Some people consider a pyramid scheme to be a type of scam.