Islam

=== Shia ===
{{Main|Shia Islam}}
[[File:حرم_الامام_الحسين.jpg|thumb|The [[Imam Husayn Shrine|Imam Hussein Shrine]] in [[Islam in Iraq|Iraq]] is a holy site for [[Shia Islam in Iraq|Shia Muslims]].]]
[[File:001123-AbolfazlShrine-BetweenTheHolyShrines-Karbala-IMG 7729-2.jpg|thumb|[[Al-Abbas Shrine]], Between The Holy Shrines, [[Karbala]], [[Iraq]].]]
Shia Islam, or Shi'ism, is the second-largest Muslim denomination.<ref name="CIA Factbook">{{cite web |title=Field Listing :: Religions |url=https://www.cia.gov/library/publications/the-world-factbook/fields/2122.html |url-status=dead |archive-url=https://web.archive.org/web/20100706231326/https://www.cia.gov/library/publications/the-world-factbook/fields/2122.html |archive-date=6 July 2010 |access-date=25 October 2010 |website=[[The World Factbook]] |publisher=[[Central Intelligence Agency]] |quote=Sunni Islam accounts for over 75% of the world's Muslim population." ... "Shia Islam represents 10–15% of Muslims worldwide.}}</ref><ref name="berkleycenter-sunni">{{cite web |title=Sunni |url=https://berkleycenter.georgetown.edu/essays/sunni |url-status=dead |archive-url=https://web.archive.org/web/20200614103622/https://berkleycenter.georgetown.edu/essays/sunni |archive-date=14 June 2020 |access-date=24 May 2020 |publisher=[[Berkley Center for Religion, Peace, and World Affairs]] |quote=Sunni Islam is the largest denomination of Islam, comprising about 85% of the world's over 1.5 billion Muslims.}}</ref>{{sfnp|Pew Forum for Religion & Public Life|2009|p=1|ps=. "Of the total Muslim population, 10–13% are Shia Muslims and 87–90% are Sunni Muslims."}} Shias, or Shiites, split with Sunnis over Muhammad's [[Succession to Muhammad|successor]] as leader, who the Shia believed must be from certain descendants of Muhammad's family known as the [[Ahl al-Bayt]] and those leaders, referred to as [[Imamate in Shia doctrine|Imam]]s, have additional spiritual authority.<ref>{{cite encyclopedia|url=https://www.britannica.com/topic/Shii|title=Shiʿi|last=Newman|first=Andrew J.|publisher=Encyclopedia Britannica|access-date=28 December 2021|archive-date=20 July 2019|archive-url=https://web.archive.org/web/20190720054917/https://www.britannica.com/topic/Shii|url-status=live}}</ref><ref name="EMMENA">{{Cite encyclopedia |year=2004 |title=Sunni Islam |encyclopedia=The Encyclopedia of the Modern Middle East and North Africa |publisher=[[Macmillan Publishers|MacMillan]] Reference |editor-last=Philip Mattar |edition=2nd |author=Tayeb El-Hibri, Maysam J. al Faruqi}}</ref> 

According to both Sunni and Shia Muslims, significant event that took place at [[Ghadir Khumm]], during Muhammad's return from his final pilgrimage to Mecca. At Ghadir Khumm, Muhammad appointed his cousin [[Ali]] as the executor of his last will and testament, as well as his [[Wali]] (authority).<ref>{{Cite book|last=Veccia Vaglieri|first=L.|date=2012|title=Encyclopaedia of Islam|url=https://referenceworks.brillonline.com/entries/encyclopaedia-of-islam-2/*-SIM_2439|section=G̲h̲adīr K̲h̲umm|publisher=Brill|access-date=July 14, 2023|isbn=9789004161214|archive-date=14 July 2023|archive-url=https://web.archive.org/web/20230714174420/https://referenceworks.brillonline.com/entries/encyclopaedia-of-islam-2/*-SIM_2439|url-status=live}}</ref>{{sfnp|Campo|2009|pp=257–258}} Shias recognise that Muhammad nominated [[Ali]] as his successor (khalīfa) and [[Imamate in Shia doctrine|Imam]] (spiritual and political leader) after him.<ref name="jaarel 2015">{{cite journal |last=Foody |first=Kathleen |date=September 2015 |title=Interiorizing Islam: Religious Experience and State Oversight in the Islamic Republic of Iran |editor-last=Jain |editor-first=Andrea R. |journal=[[Journal of the American Academy of Religion]] |volume=83 |issue=3 |pages=599–623 |doi=10.1093/jaarel/lfv029 |doi-access=free |location=Oxford |publisher=[[Oxford University Press]] on behalf of the [[American Academy of Religion]] |eissn=1477-4585 |issn=0002-7189 |jstor=24488178 |lccn=sc76000837 |oclc=1479270 |quote=For Shiʿi Muslims, Muhammad not only designated Ali as his friend, but appointed him as his successor—as the "lord" or "master" of the new Muslim community. Ali and his descendants would become known as the Imams, divinely guided leaders of the Shiʿi communities, sinless, and granted special insight into the Qurʾanic text. The theology of the Imams that developed over the next several centuries made little distinction between the authority of the Imams to politically lead the Muslim community and their spiritual prowess; quite to the contrary, their right to political leadership was grounded in their special spiritual insight. While in theory, the only just ruler of the Muslim community was the Imam, the Imams were politically marginal after the first generation. In practice, Shiʿi Muslims negotiated varied approaches to both interpretative authority over Islamic texts and governance of the community, both during the lifetimes of the Imams themselves and even more so following the disappearance of the twelfth and final Imam in the ninth century.}}</ref> Some of the first Imams are revered by all Shia groups and Sunnis, such as Ali. The [[Twelvers]], the largest Shia branch, believe in [[twelve Imams]], the last of whom went into [[Occultation (Islam)|occultation]] to return one day. They recognise that the prophecy of the Twelve Imams has been foretold in the [[Hadith of the Twelve Successors]] which is recorded by both Sunni and Shia sources.<ref>{{Cite journal|last=Kohlberg|first=Etan|title=From Imāmiyya to Ithnā-'ashariyya|url=https://www.cambridge.org/core/journals/bulletin-of-the-school-of-oriental-and-african-studies/article/abs/from-imamiyya-to-ithnaashariyya/32F60507F79BEE8C3732011F4D092CAF|journal=Bulletin of the School of Oriental and African Studies|year=1976|volume=39|issue=3|pages=521–534|doi=10.1017/S0041977X00050989|s2cid=155070530|access-date=July 14, 2023|archive-date=14 July 2023|archive-url=https://web.archive.org/web/20230714174420/https://www.cambridge.org/core/journals/bulletin-of-the-school-of-oriental-and-african-studies/article/abs/from-imamiyya-to-ithnaashariyya/32F60507F79BEE8C3732011F4D092CAF|url-status=live}}</ref>

[[Zaidism]] rejects special powers of Imams and are sometimes considered a 'fifth school' of Sunni Islam rather than a Shia denomination.<ref name=Arab-IsraeliConflict>{{cite book |title=The Encyclopedia of the Arab-Israeli Conflict: A Political, Social and Military History |editor-first1=Spencer C. |editor-last1=Tucker |editor2=Priscilla Mary Roberts |year=2008 |publisher=ABC-CLIO |isbn=978-1-85109-842-2 |page=917 |url=https://books.google.com/books?id=YAd8efHdVzIC&pg=PA917 |access-date=20 June 2015 |archive-date=28 December 2023 |archive-url=https://web.archive.org/web/20231228024726/https://books.google.com/books?id=YAd8efHdVzIC&pg=PA917 |url-status=live }}</ref><ref name=IraqEffect>{{cite book |title=The Iraq Effect: The Middle East After the Iraq War |first=Frederic M. |last=Wehrey |year=2010 |publisher=Rand Corporation |isbn=978-0-8330-4788-5 |page=91 |url=https://books.google.com/books?id=i-3LAlfW7DIC&pg=PA91 |access-date=20 June 2015 |archive-date=28 December 2023 |archive-url=https://web.archive.org/web/20231228024742/https://books.google.com/books?id=i-3LAlfW7DIC&pg=PA91#v=onepage&q&f=false |url-status=live }}</ref> They differed with other Shias over the status of the fifth imam and are sometimes known as "Fivers".<ref>{{Cite journal |last=Peterson |first=Daniel |title=Zaydiyya |url=|journal=Islamic Studies |year=2011 |language=en |volume= |issue= |pages= |doi=10.1093/obo/9780195390155-0153 |issn=}}</ref> The [[Ismailism|Isma'ilis]] split with the Twelvers over who was the seventh Imam and have split into more groups over the status of successive Imams, with the largest group being the [[Nizari Isma'ilism|Nizari]]s.<ref name="Newman2013">{{cite book|last=Newman|first=Andrew J.|author-link=Andrew J. Newman|title=Twelver Shiism: Unity and Diversity in the Life of Islam, 632 to 1722|url=https://books.google.com/books?id=-_M8BQAAQBAJ|year=2013|publisher=Edinburgh University Press|isbn=978-0-7486-7833-4|chapter=Introduction|chapter-url=https://books.google.com/books?id=-_M8BQAAQBAJ&pg=PP18|page=2|access-date=13 October 2015|archive-url=https://web.archive.org/web/20160501201413/https://books.google.com/books?id=-_M8BQAAQBAJ|archive-date=1 May 2016|url-status=live}}</ref>