Official Resource The American Society of Clinical Hypnosis -- http://www.asch.net

Short Definition
Hypnotherapy is a technique using hypnosis that reaches into the subconscious mind for solutions to problems with which the conscious mind has been unable to deal. Hypnotherapy has been used to treat addictions, relieve stress and help individuals develop a more positive attitude in general. Many people have learned to hypnotize themselves as a regular adjunct to their daily lives.

Expanded Information
First developed by Anton Mesmer (1734-1815), hypnotic techniques can induce everything from a light to a heavy hypnotic state to help a client overcome psychological or physical problems. From helping people to overcome a craving for cigarettes to managing chronic pain from an illness or accident, trained hypnotherapists work with a wide variety of problems.

The clinical use of hypnosis, in which the subject's powers of concentration are mobilized and subconscious memories and perceptions brought into consciousness. Hypnotherapists usually relax their patients progressively, often by using a countdown procedure or relaxing the body limb by limb from the feet to the head. Once the subject has entered an altered state of consciousness--in effect a light state of trance--the practitioner then provides cues which allow the subject to overcome personal barriers and emotional blockages, and to bring into awareness faculties and abilities which had been formerly neglected.

In hypnosis trance, one can be helped to access inner resources and potentials for healing and improved performance. It can help you get in touch with your inner resources and "inner strength".

Hypnosis can help you communicate with and develop a relationship with your own subconscious. In a state of deep relaxation, with your permission, a "doorway" to your subconscious is somehow opened. Then, with your receptivity and permission, you may be able to absorb acceptable and appropriate therapeutic information if it is provided in a language and form that is acceptable to you.

In hypnosis, a divided state of attention or consciousness is induced. While your conscious mind is pleasantly absorbed in relaxing, enjoyable sensations, a pleasant memory, or an imaginative fantasy, your subconscious attends to the communication that initiated or continues to maintain the hypnosis altered state. So, it is like you are here and there at the same time.

Your conscious mind may be on the beach (or wherever your favorite place is), but your subconscious is functioning like a “hidden observer”. Now here’s the clincher: to the degree that the initiating communication (the hypnosis induction) is compelling, engaging, and absorbing, the division or split in consciousness is heightened or deepened. And, the deeper the split in consciousness is, the more your unconscious or "hidden observer" is awakened and responsive to the initiating hypnotic communication!

When your subconscious is very responsive, your responses to hypnotic suggestions feel automatic, spontaneous, and involuntary. They just happen easily and comfortably with little or no conscious deliberation. So when you begin to learn and experience self-hypnosis with the help of a qualified hypnotherapist, you are likely to have a range of responses. The depth of the division in your consciousness will vary. But what is most important is not the depth of this division or split, but rather the quality of your experience.

When your body is comfortably relaxed and at ease and your conscious mind is absorbed in an interesting experience involving compelling sensory imagery, your inner mind or unconscious mind is alerted to pay attention. This frees your inner mind to be open and receptive to acceptable positive ideas and suggestions. Once your inner mind accepts an idea, it transforms that idea into a reality. This can help you change your experience in the way that you desire.

Hypnosis is easier than you may think. The induction of self-hypnosis first involves resting, giving yourself permission to be at ease, and letting go of tensions. While you restfully ease into relaxation without falling asleep, you become absorbed in your pleasant experience and redirect your focus of attention.

Source: http://www.hypnosisgroup.com/hypnosis/