Adherents of Shia Islam are called Shias or the Shi'a as a collective or Shi'i individually. Shi'a is the short form of the historic phrase Shīʻatu ʻAlī meaning "followers", "faction" or "party" of Muhammad's son-in-law and cousin Ali, whom the Shia believe to be Muhammad's successor in the Caliphate. Twelver Shia (Ithnā'ashariyyah) is the largest branch of Shia Islam, and the term Shia Muslim is often taken to refer to Twelvers by default. Template:As of Shia Muslims constituted 10-13% of the world's Muslim population, Shias comprised 11-14% of the Muslim population in the Middle East-North Africa region, and between 68% and 80% of Shias lived in four countries: Iran, Pakistan, India and Iraq.
Shia Islam is based on the Quran and the message of the Islamic prophet Muhammad attested in hadith recorded by the Shia, and certain books deemed sacred to the Shia (Nahj al-Balagha). Shia consider Ali to have been divinely appointed as the successor to Muhammad, and as the first Imam. The Shia also extend this "Imami" doctrine to Muhammad's family, the Ahl al-Bayt ("the People of the House"), and certain individuals among his descendants, known as Imams, who they believe possess special spiritual and political authority over the community, infallibility, and other divinely-ordained traits. Although there are myriad Shia subsects, modern Shia Islam has been divided into three main groupings: Twelvers, Ismailis and Zaidis with Twelver Shia being the largest and most influential group among Shia.
- Shi'a is an alternative spelling of Shia, and Shi'ite of Shiite. In subsequent sections, the spellings Shia and Shiite are adopted for consistency, except where the alternative spelling is in the title of a reference.
- "Mapping the Global Muslim Population", http://www.pewforum.org/2009/10/07/mapping-the-global-muslim-population/.
- Esposito, John. "What Everyone Needs to Know about Islam." Oxford University Press, 2002 | ISBN 978-0-19-515713-0. p. 40
- "From the article on Shii Islam in Oxford Islamic Studies Online", Oxfordislamicstudies.com, http://www.oxfordislamicstudies.com/article/opr/t125/e2189?_hi=26&_pos=238.
- "Lesson 13: Imam’s Traits", Al-Islam.org, http://www.al-islam.org/principles-shiite-creed-ayatullah-ibrahim-amini/lesson-13-imams-traits.
- Tabataba'i (1979), p. 76
- God's rule: the politics of world religions - Page 146, Jacob Neusner - 2003
- "Shīʿite", Encyclopædia Britannica Online, 2010, http://www.britannica.com/EBchecked/topic/540503/Shiite.
- Esposito, John. "What Everyone Needs to Know about Islam," Oxford University Press, 2002. ISBN 978-0-19-515713-0. p.40