Hypnosis is a psychological state with physiological attributes superficially resembling sleep and marked by an individual’s level of awareness other than the ordinary conscious state. Another description of the phenomenon is that of an altered mental state, while another links it to imaginative role-enactment.

A person under hypnosis is said to have heightened focus and concentration with the ability to concentrate intensely on a specific thought or memory, while blocking out sources of distraction. Hypnosis is usually induced by a procedure known as a hypnotic induction involving a series of preliminary instructions and suggestions. 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”.

Hypnosis typically involves an introduction to the procedure during which the subject is told that suggestions for imaginative experiences will be presented. The hypnotic induction is an extended initial suggestion for using one’s imagination, and may contain further elaborations of the introduction. A hypnotic procedure is used to encourage and evaluate responses to suggestions.

When using hypnosis, one person (the subject) is guided by another (the hypnotist) to respond to suggestions for changes in subjective experience, alterations in perception, sensation, emotion, thought or behavior. Persons can also learn self-hypnosis, which is the act of administering hypnotic procedures on one’s own. If the subject responds to hypnotic suggestions, it is generally inferred that hypnosis has been induced.