Jean-Martin Charcot, of the Salpêtrière hospital, Paris, demonstrates hypnosis on a patient supported by his assistant

Advertisement poster of 1857:
"Instant sleep. Miscellaneous effects of paralysis, partial and complete catalepsy, partial or complete attraction. Phreno-magnetic effects... Musical ecstasy... Insensitivity to physical pain and instant awakening... transfusion of magnetic power to others..."

Hypnosis is "a trance state characterized by extreme suggestibility, relaxation and heightened imagination".It is an altered state of consciousness.

Usually, one person (the "hypnotist") talks to another (the "subject") in a special way that puts the subject into a trance. While the subject is in this state, he can be influenced by suggestions. The hypnotist can tell him to forget his name, or that the room is hot (he will start sweating), or that he is someone else. Hypnotic suggestions may be delivered by a hypnotist in the presence of the subject, or may be self-administered ('self-suggestion' or 'autosuggestion'). The use of hypnotism for therapeutic purposes is referred to as 'hypnotherapy', while its use as a form of entertainment for an audience is known as 'stage hypnosis'.