Imam Ali Shrine in the context of "Sunni Muslims"

Shia Islam is the second-largest branch of Islam. It holds that Muhammad designated Ali ibn Abi Talib (r. 656–661) as both his political successor (caliph) and as the spiritual leader of the Muslim community (imam). However, his right is understood to have been usurped by a number of Muhammad's companions at the meeting of Saqifa, during which they appointed Abu Bakr (r. 632–634) as caliph instead. As such, Sunni Muslims believe Abu Bakr, Umar (r. 634–644), Uthman (r. 644–656) and Ali to be 'rightly-guided caliphs', whereas Shia Muslims regard only Ali as the legitimate successor.

Shia Muslims believe that the imamate continued through Ali's sons, Hasan and Husayn, after which various Shia branches developed and recognized different imams. They revere the ahl al-bayt, the family of Muhammad, maintaining that they possess divine knowledge. Shia holy sites include the shrine of Ali in Najaf, the shrine of Husayn in Karbala, and other mausoleums of the ahl al-bayt. Later events, such as Husayn's martyrdom in the Battle of Karbala (680 CE), further influenced the development of Shia Islam, contributing to the formation of a distinct religious sect with its own rituals and shared collective memory.

Najaf is the capital city of the eponymous Najaf Governorate in central Iraq, about 160 km (99 mi) south of Baghdad. Its estimated population in 2024 was about 1.41 million people. It is widely considered amongst the holiest cities of Shia Islam and one of its spiritual capitals, as well as the center of Shia political power in Iraq.

It is the burial place of Muhammad's son in law and cousin, ‘Alī ibn Abī Tālib, and thus a major pilgrimage destination for Shia Muslims. The largest cemetery in the world (Wadi-us-Salaam) and the oldest Shi'a Islamic seminary in the world (Hawza of Najaf) are located in Najaf.

Wadi-us-Salaam is an Islamic cemetery, located in the holy city of Najaf, Iraq. It is the largest cemetery in the world. The cemetery covers 1,485.5 acres (601.16 ha; 6.01 km; 2.32 sq mi) and contains more than 6 million bodies. It also attracts millions of pilgrims annually.

The cemetery is located near the shrine of Ali ibn Abi Talib, the fourth Sunni Caliph, as well as the first Shia Imam. Thus, many Shi'ites in Iraq request that they be buried in this cemetery. As a result of improved transportation methods, Shi'ites from across the globe are (or seek to be) buried in the cemetery. Modern burials are interred inside shared crypts.

The Najaf Seminary (Arabic: حوزة النجف), also known as the al-Hawza al-Ilmiyya (الحوزة العلمية), is the oldest and one of the most important Shia seminaries (hawza) in the world. It is located near the Imam Ali Shrine in the city of Najaf in Iraq, and also operates a campus in Karbala.

Grand Ayatollah Sayed Ali al-Sistani currently serves as head of the Hawza Al-Ilmiyya in Najaf, which includes two other Ayatollahs - Mohammad Ishaq Al-Fayyad and Bashir al-Najafi. The number of students studying there has waxed and waned in modern times, from 15,000 to 20,000 in the mid-20th century, down to 3000 during the repressive reign of Saddam Hussein, to around 13,000 as of 2014.