Hypnotism is widely known by stage performances in which people are coaxed into embarrassing situations. As it turns out, this type of show has little to do with the actual work of legitimate practitioners: Professional hypnotists have helped people stop smoking, lose weight, manage anxiety and deal with pain, among other accomplishments. First recognized in the late 1700s, hypnosis entails harnessing the power of the mind to impact one's perception and behavior.