Multiple Personality Disorder, now known as Dissociative Identity Disorder (DID), is a rare dissociative disorder characterized by two or more distinct identities within an individual, often arising from childhood trauma and genetic factors. Symptoms include memory loss, mental health issues, and a blurred sense of identity, and treatment typically involves psychotherapy, medications, and hypnosis, requiring several years for effective management. The disorder affects a higher proportion of women and is often misdiagnosed due to a lack of awareness among healthcare providers.