Hypnosis -- or hypnotherapy -- uses guided relaxation, intense concentration, and focused attention to achieve a heightened state of awareness that is sometimes called a trance. The person's attention is so focused while in this state that anything going on around the person is temporarily blocked out or ignored. In this naturally occurring state, a person may focus his or her attention -- with the help of a trained therapist -- on specific thoughts or tasks.
Braid can be taken to imply, in later writings, that hypnosis is largely a state of heightened suggestibility induced by expectation and focused attention. In particular, Hippolyte Bernheim became known as the leading proponent of the "suggestion theory" of hypnosis, at one point going so far as to declare that there is no hypnotic state, only heightened suggestibility. There is a general consensus that heightened suggestibility is an essential characteristic of hypnosis. In 1933, Clark L. Hull wrote:

Before long, hypnotism started finding its way into the world of modern medicine. The use of hypnotism in the medical field was made popular by surgeons and physicians like Elliotson and James Esdaille and researchers like James Braid who helped to reveal the biological and physical benefits of hypnotism.[50] According to his writings, Braid began to hear reports concerning various Oriental meditative practices soon after the release of his first publication on hypnotism, Neurypnology (1843). He first discussed some of these oriental practices in a series of articles entitled Magic, Mesmerism, Hypnotism, etc., Historically & Physiologically Considered. He drew analogies between his own practice of hypnotism and various forms of Hindu yoga meditation and other ancient spiritual practices, especially those involving voluntary burial and apparent human hibernation. Braid's interest in these practices stems from his studies of the Dabistān-i Mazāhib, the "School of Religions", an ancient Persian text describing a wide variety of Oriental religious rituals, beliefs, and practices.
The first neuropsychological theory of hypnotic suggestion was introduced early by James Braid who adopted his friend and colleague William Carpenter's theory of the ideo-motor reflex response to account for the phenomenon of hypnotism. Carpenter had observed from close examination of everyday experience that, under certain circumstances, the mere idea of a muscular movement could be sufficient to produce a reflexive, or automatic, contraction or movement of the muscles involved, albeit in a very small degree. Braid extended Carpenter's theory to encompass the observation that a wide variety of bodily responses besides muscular movement can be thus affected, for example, the idea of sucking a lemon can automatically stimulate salivation, a secretory response. Braid, therefore, adopted the term "ideo-dynamic", meaning "by the power of an idea", to explain a broad range of "psycho-physiological" (mind–body) phenomena. Braid coined the term "mono-ideodynamic" to refer to the theory that hypnotism operates by concentrating attention on a single idea in order to amplify the ideo-dynamic reflex response. Variations of the basic ideo-motor, or ideo-dynamic, theory of suggestion have continued to exercise considerable influence over subsequent theories of hypnosis, including those of Clark L. Hull, Hans Eysenck, and Ernest Rossi.[40] It should be noted that in Victorian psychology the word "idea" encompasses any mental representation, including mental imagery, memories, etc.

In the 2000s, hypnotherapists began to combine aspects of solution-focused brief therapy (SFBT) with Ericksonian hypnotherapy to produce therapy that was goal focused (what the client wanted to achieve) rather than the more traditional problem focused approach (spending time discussing the issues that brought the client to seek help). A solution-focused hypnotherapy session may include techniques from NLP.[13]
Although there are different techniques, clinical hypnotherapy is generally performed in a calm, therapeutic environment. The therapist will guide you into a relaxed, focused state and ask you to think about experiences and situations in positive ways that can help you change the way you think and behave. Unlike some dramatic portrayals of hypnosis in movies, books, or on stage, you will not be unconscious, asleep, or in any way out of control of yourself. You will hear the therapist’s suggestions, but it is up to you to decide whether or not to act on them.