The discovery of hypnosis has led to three different theories on What is hypnosis namely role theory, altered-state theory, and dissociation theory.
Whether or not you believe that hypnosis is an altered state of consciousness (i.e. altered-state theory), the key characteristic of hypnotic responding is involuntariness.
This is known as the "classic suggestion effect" by André Muller Weitzenhoffer, who was one of the most prolific researchers in the field of hypnosis in the latter half of the 20th century.
When a subject carries out a hypnotic suggestion, they experience the behaviour as happening all by itself, involuntarily.
For example, if the suggestion implies that the subject's arm is rigid like a bar of iron, the classic hypnotic experience is that the person's arm truly becomes rigid, on its own, without deliberately holding it stiffly.
While attempting to experience hypnosis, it is important to remember the following things:
When you notice that you are noticing these sensations, do not become alarmed or you may shock yourself right out of the hypnotic state.
Don't try too hard to get into a hypnotic state, just expect the hypnotic state to occur gradually and it will.
Suggestions stay with some individuals indefinitely, others need reinforcement.
The effects of hypnosis are cumulative: The more you practice the techniques and incorporate posthypnotic suggestions, the more permanent the results become.