Hypnosis is a deep state of relaxation during which positive suggestions are made to the subconscious mind, bringing about beneficial changes. You will feel peaceful as your conscious mind rests. This is the overly critical part of the mind which often prevents you from making the changes you wish to make.
The subconscious mind controls habits and other things that we do automatically. It is fueled by our emotions and imagination. The subconscious mind also contains memories of everything that we have ever experienced. During hypnosis, your subconscious mind is very focused, allowing learning to happen quickly.
Hypnotherapy is not about mind control. In hypnosis the mind is very receptive to new ideas and open to suggestions which encourage more sensible, balanced and helpful attitudes.
The number of sessions required varies from person to person however most people feel some benefit from hypnotherapy immediately and most make the changes they wish to make in only three to five sessions.