3. Explain what Twelver Shiism is

Twelver Shi'a Islam or Imamiyyah is the largest branch of Shi'a Islam. The term Twelver refers to its adherents' belief in twelve divinely ordained leaders, known as the Twelve Imams, and their belief that the Mahdi will be the returned Twelfth Imam who disappeared and is believed by Twelvers to be in occultation.