People have tried to answer this question for over 200 years, but science has yet to fully explain how it actually happens.
Simply put, hypnosis is a state of trance characterized by extreme suggestibility, relaxation, and heightened imagination. Unlike sleep, the subject is alert the whole time.
Hypnosis is compared to daydreaming or zoning out. In hypnosis, you’re fully conscious, tuned out most of the stimuli around you. You focus intently on the subject at hand, such as a movie or a book for example.
In hypnosis, you are also highly suggestible. That means that when a hypnotherapist suggests something, such as a new idea or a new belief for example, when the hypnotist tells you to do something, you’ll probably embrace the idea completely.