Link:

For various reasons, a person might act very differently in different situations. Clark Kent works at his newspaper, but when Metropolis is in danger, he puts on a cape and becomes Superman. Dr. Jekyll has a quiet Victorian life in London, but at night becomes a terrible monster named Mr. Hyde. "Ego" is a term from psychoanalysis and in this context means "personality" or "character". "Alter" is short for "alternative" which means "the other". So someone's "alter ego" is the other personality they behave as for one or another reason.

If someone leads a double life, or has two separate personalities, then their alter ego is their second life or second personality.

we all have an alter ego, it's that part of our personality that we seldom show. Typical only very close friends or family members would know our alternative self. In fiction, it is characters like Superman and the incredible hulk In drama or comedy it is the funny or sad part we see an actor portray, but in their personal life, they are the opposite. good examples are some comedians they are funny on stage but often racked with depression in real life. in classical plays, the stories are often about a person with an alter ego, if you have two distinct sets of friends you have an alter ego. if you are one personality at school or work but another at home you have an alter ego.

a person's secondary or alternative personality.