Is hypnosis just hocus-pocus?

Dressed in a flowing cape, 16th-century physician Franz Anton Mesmer merely had to touch his suggestive patients with a magnetic wand for them to experience wild laughter, crying and shrieking. So what is hypnosis? Do hypnotized people enter a sleep-like state in which they forego their willpower, are oblivious to their surroundings and forget what happened afterwards?