Psychology is the science of human experience and behavior and is also called the science of the soul. But this is a very fuzzy definition, because the term soul can not actually be defined and the behavior and experience of humans is also very malleable. In order to make this more measurable and tangible, psychology uses mental, social and natural scientific models of thought. In addition, there are various sub-fields of psychology, which includes clinical psychology. For example, one method of clinical psychology is hypnosis. Modern and serious hypnosis (clinical hypnosis) is used to treat anxiety, break bad habits, relieve pain or reduce stress, among other things.