Twelver Shīʿism (ٱثْنَا عَشَرِيَّة; DIN), also known as Imāmiyya (إِمَامِيَّة), is the largest branch of Shīʿa Islam, comprising about 85 percent of all Shīʿa Muslims. The term Twelver refers to its adherents' belief in twelve divinely ordained leaders, known as the Twelve Imams, and their belief that the last Imam, Imam al-Mahdi, lives in Occultation and will reappear as the promised Mahdi (المهدي المنتظر).
Twelvers believe that the Twelve Imams are the spiritual and political successors to the Islamic prophet Muhammad. According to the theology of Twelvers, the Twelve Imams are exemplary human individuals who not only rule over the Muslim community (Ummah) with justice, but are also able to preserve and interpret the Islamic law (sharīʿa) and the esoteric meaning of the Quran. The words and deeds (sunnah) of Muhammad and the Imams are a guide and model for the Muslim community to follow; as a result, Muhammad and the Imams must be free from error and sin, a doctrine known as Ismah or infallibility, and must be chosen by divine decree, or nass, through Muhammad.
There are approximately 150 million to 200 million Twelvers in the world today, making the majority of the total populations of Iran, Iraq, Bahrain and Azerbaijan. Twelvers represent half of the Muslim population in Lebanon, and a sizable minority in India, Pakistan, Afghanistan, Saudi Arabia, Bangladesh, Kuwait, Oman, UAE, Qatar, Nigeria, Chad, and Tanzania. Iran is the only country where Twelver Shi'ism is the state religion.
Twelvers share many tenets with other Shīʿīte sects, such as the belief in the Imamate, but the Ismāʿīlī and Nizārī branches believe in a different number of Imams and, for the most part, a different path of succession regarding the Imamate. They also differ in the role and overall definition of an Imam. Twelvers are also distinguished from Ismāʿīlīs by their belief in Muhammad's status as the "Seal of the Prophets" (Khatam an-Nabiyyin), in rejecting the possibility of abrogation of sharīʿa laws, and in considering both esoteric and exoteric aspects of the Quran.
