Alter ego (Latin which means "I am the other") is the second self that is believed to be different than the average person or the real personality. This term was used in the early nineteenth century when personality breakdown disorders were first explained by psychologists [1]. Someone who has Alter ego is said to live a double life.

A different meaning from Alter ego can be found in literary analysis, which depicts characters in different works that are psychologically similar, or fictional characters whose behavior, speech, or mind deliberately represent the author [2] or with other types of appearance.

The existence of "another self" was first recognized in the 1730s. Anton Mesmerm uses hypnosis to separate Alter ego. This experiment shows a different pattern of behavior from the individual's personality in a conscious state than when hypnotized. Other characters are developed in changing consciousness but in the same body [3].

Alter ego is also used to refer to different behaviors of each person displayed in certain circumstances