Hypnosis primarily defines the process by which acceptable suggestion is executed by the mind. Execution presumes the bypass of the critical factor of the mind whose function is to filter out suggestions.
Hypnosis is also defined as a specific state of altered consciousness characterized by intense focused attention.
Scientific studies of hypnosis generally explore hypnosis as a state. Various imaging studies support the hypothesis that there is in fact a state of hypnosis and it is a phenomenon which can be induced so as to produce changes in brain function. Clinical studies show that various phenomena such as anesthesia and amnesia can be achieved using hypnosis.
I think hypnosis is synonymous with compliance. How it works is explained through theories of communication, negotiation and influence. The most important precursor to explaining how it works is proposing a mind model. You can image search hypnosis mind model or NLP mind model on google for a quick reference.
