Multiple personalities, or Dissociative Identity Disorder (DID), is a rare mental disorder characterized by the presence of two or more distinct identities that control behavior and cause memory lapses. The disorder affects approximately 0.01% to 1% of the population, with many patients misdiagnosed and taking an average of 6 to 7 years to receive the correct diagnosis. While there is no cure, treatment through medication and therapy can help individuals lead healthy lives despite the presence of multiple personalities.