All hypnosis is self hypnosis, in other words a therapist will give you instructions to imagine things in a certain way and it is up to you to follow those instructions.
It is an altered state of consciousness into which you allow yourself to enter, with the guidance of a therapist. You are in control all the time, you always know what is happening, and you can come out of the altered state at any time in the same way one can snap out of a vivid daydream.
The hypnotic state can feel as if you are dreaming or daydreaming and is a natural form of consciousness which many people experience on a daily basis.
For example if you have ever been so absorbed in a book or a film it has felt as if you are actually there, that is a form of Hypnosis, as is the experience some people have when waking in the morning being aware of everything going on around them yet still being in a very relaxed dream like state.
Within the hypnotic state one can by-pass the barriers to our inner thoughts and feelings, and suggestions are acted upon much more powerfully than is possible in a normal state of mind.
Mental imagery can also be utilised to assist people to make changes in their lives. The subconscious mind does not distinguish between ´real` and imagined` experiences, which is why dreams can feel real.
This phenomenon can be used so that clients can create new positive realities for themselves or alter their perception of past events which may affect current behaviour.
There is also a growing body of scientific knowledge, psychoneuroimmunology, which is showing that the mind is directly linked to our immune systems, which means that techniques used in hypnotherapy can also affect our physical as well as psychological and spiritual well-being.