So what is hypnosis, exactly? The word comes from the Greek for sleep, or hypno, which is exactly what it is not. Hypnosis is not a state of sleep or unconsciousness - in fact, many report a sense of greater awareness while in trance. The term merely comes from the appearance of the subjects; they appear to be asleep - eyes closed, very relaxed, breathing slowly and deeply - similar to meditation.
The actual experience of hypnosis is very common and natural, something we all do a few or several times daily. Daydreaming is a good example. The eyes are open, but the mind is far, far away, on a beautiful deserted island. Perhaps you've been on a long or familiar drive, arrived at your destination safely, but couldn't remember parts of the drive. Getting so involved with a fictional film or book that you had an urge to cry or experienced some other emotion. These are all natural "trance" states that most of us have experienced many times. All hypnosis amounts to is directing this ability we all possess (creative imagination) to cause the subconscious part of the mind to bring about a change in a particular behavior. With repetition, the change becomes permanent. Remember that all of your learned habits and behaviors are stored in your mind on a subconscious level, so changing them means change on that level as well.