Hypnosis and Behavior Modification

The hypnotic or trance state is a state of consciousness whereby the subject has a greater awareness (awareness of what?)

In the hypnotic state, the subject's subconscious mind is more open to suggestion.   Ordinarily, the conscious mind acts as a filter and guardian for the data which all of us are bombarded with.   Often, the conscious mind does not make good decisions as to what data should make an impression on the subconscious mind. (Have an article describing what the conscious and subconscious minds are)

Hypnosis is usually performed in a controlled environment.   You are opening your mind to suggestions that you want to implant in your subconscious, rather than letting rubbish flow in. (maybe do a Garbage In, Garbage Out article)

A skilled hypnotist is not just someone who can lead a subject into a trance state.   A skilled hypnotist also knows how to correctly feed appropriate suggestions to the subject, once in the trance state, so that the suggestions are impressed upon the subconscious mind and the desired behavioral changes or other results are achieved.

Hypnosis is often linked with techniques such as Neuro-Linguistic Programming (explain) and other psychological analysis and treatment techniques to alter behavior.