Covert Hypnosis is the ability to subtly communicate with another person's subconscious mind without them noticing. The objective is to change the intended behaviour - a sales person, for example, telling the client how good she will feel buying the new product. An intentional use of carefully selected words, body language, intentional gestures that seem commonplace (pointing in a certain direction) and facial expressions (a frown to the buyer to convey the unspoken opinion that she is making a mistake) in order to covertly communicate with someone's subconscious mind. The final objective is to have the person make their own decision to change their mind.

It is a form of hypnosis attempting to achieve near hypnotic states in the listener (sometimes called "sleight of mouth"). ) In covert hypnosis the subject is unaware that the hypnotist is either a hypnotist, or hypnotising them, or that anything out of the ordinary is occurring.

Covert hypnosis is a phenomenon not too different from indirect hypnosis (as derived from Milton H. Erickson popularised as The Milton Model http://nlpuniversitypress.com/html2/Mi-My08.html) 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 which the subject isn't fully consciously aware the meaning of.