There doesn’t seem to be a consensus explaining exactly what hypnosis is. You’ll find a different definition in each place you look. Here is my best definition:
Hypnosis is an altered state of consciousness in which the subject has heightened suggestibility, within certain limitations. He/she can access creativity, reprogram old patterns, overcome limiting beliefs, reduce stress, work with pain relief, and access hidden strengths.
An altered state of consciousness, or trance state, is a normal and natural state that almost everyone goes in and out of multiple times each day. For instance; most people have experienced being in a boring class or meeting where, without even realizing it, they “go somewhere else” in their minds and are abruptly brought back to the present when asked a question. Daydreaming is common trance state. Driving on autopilot is another. Becoming so focused on a book or movie or problem such that everything else fades out around you is another common trance state. Hypnosis is simply a guided trance state.