Everyone has experienced a trance many times, but we don't usually call it hypnosis. While we were zoned out, another level of consciousness, which we refer to as our unconscious mind, took over. These are very focused states of attention similar to hypnosis. Clinical hypnotists do essentially three things with hypnosis. They encourage the use of imagination.
Mental imagery is very powerful, especially in a focused state of attention.
The mind seems capable of using imagery, even if it is only symbolic, to assist us in bringing about the things we are imagining. For example, a patient with ulcerative colitis may be asked to imagine what her distressed colon looks like. Another basic hypnotic method is to present ideas or suggestions to the patient. In a state of concentrated attention, ideas and suggestions that are compatible with what the patient wants seem to have a more powerful impact on the mind. Finally, hypnosis may be used for unconscious exploration, to better understand underlying motivations or identify whether past events or experiences are associated with causing a problem.