Sunnis believe that Muhammed did not appoint a successor. On the contrary, Shias believe that Muhammad designated Ali ibn Abi Talib - "Ali" - as his successor. 90% of Shias believe in twelve divinely ordained Imams. They are known as the Twelver and take majorities in Iran, Azerbaijan, Iraq, Bahrain and Lebanon. The rest of Shias either believe that the leader of Muslim community can only be held by any descendant from either Hasan ibn ʻAlī or Husayn ibn ʻAlī, Ali's grandsons (Zaidi, "Fiver") OR believe that Isma'il ibn Jafar was divinely appointed as spiritual successor to Ja'far al-Sadiq, wherein they differ from the Twelvers, who accept Musa al-Kadhim, younger brother of Isma'il. The later is named Ismaili or the Sevener. Their spiritual leader is currently Aga Khan IV.
— Imamzade Abdollah mosque, Hamadan, Iran