Everyone wants to know what really happens when you use covert hypnosis. We see many demonstrations of hypnotic techniques in training courses and in the media but it is difficult to accept how easily you can control someones thoughts. I'd like to share this excerpt from Wikipedia.org which clearly describes what covert hypnosis is and how it is used.
What Really Happens When You Use Covert Hypnosis?
Covert hypnosis is the ability to subtly communicate with another person's unconscious mind without their noticing. As it often takes place in the course of a seemingly regular conversation, it is also known as conversational hypnosis or sleight of mouth. The objective is to change the target’s behavior subconsciously so that the target believes that they changed their mind of their own volition. When performed successfully, the target is unaware that the practitioner has hypnotized them or that anything out of the ordinary happened.
Covert hypnosis is a phenomenon not too different from indirect hypnosis (as derived from Milton H. Erickson popularised as The Milton Model ) in style  but the defining feature is certainly the act of an individual subject becoming hypnotised and taking part in hypnotic phenomena without conscious effort/choice - covert hypnosis, like "Ericksonian Hypnosis", "operates through covert and subtle means... to reach deeper levels of consciousness than are touched by the surface structure of language"; it is the concept that an individual, 'the hypnotist,' can control another individual's behavior via gaining rapport (co-operation of their attention - as without rapport covert hypnosis does not take place)  with the subject and then making suggestions, the meanings of which the subject isn't fully consciously aware.
Building rapport is a vital step if you want to use covert hypnosis effectively. Even if you know your subject very well you still need to get them to agree with you. To learn the techniques for that click here.