Question

What is multiple personality?

Answer 1

Formerly referred to as multiple personality disorder, dissociative identity disorder, is a condition wherein a person's identity is fragmented into two or more distinct personality states.

Explanation:

Dissociative identity disorder (DID) is a severe condition in which two or more distinct identities, or personality states, are present in—and alternately take control of—an individual.

Excellent authoritative source and more details here:
https://www.psychologytoday.com/conditions/dissociative-identity-disorder-multiple-personality-disorder