Alter ego is Latin for "the other I." It refers to a person's second self or identity that is different from a person's normal personality. A person who has an alter ego is said to lead a double life. Alter ego is also used to refer to the different behaviors any person may display in certain situations.
The idea that people could have "another self" was first recognized in the 1790s. Franz Anton Mesmer, a German doctor, used hypnosis to separate his alter ego. Under hypnosis, Mesmer showed a behavior pattern that diverged from the personality he had in his waking state. It was as if a completely distinct character had developed in the altered state of consciousness, but in the same body.
Alter egos are used by numerous performing artists who use stage personas, which are different from stage names, both to entertain audiences and to explore new identities for themselves.

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