A charlatan is a person who gains the confidence of a person or group of persons by employing pseudo-science or other forms of impressive trickery. The charlatan uses the authority gained through trickery to gain influence over the people he has tricked. This use of deception to gain influence often manifests itself in sexual manipulation, the collection of money for empty services, or even political favors.
The word comes from the French world charlatan, which originally meant "a seller of medicines who might advertise his presence with music and an outdoor stage show".
The charlatan is usually a salesperson - often just a seller of ideas. The charlatan's main tactic is to impress people in order to gain their confidence and then swindle their goods. Normally, a charlatan is aware of his manipulative tactics, although it is possible that a charlatan sincerely believes his own quackery.