Ali was born at Mecca, in the Hejaz region of northern Arabia, sometime around 599 C.E.
When Muhammad reported that he had received a divine revelation, a claim that Islamic sources indicate was initially greeted with derision, Ali was one of the first to believe him and profess Islam.
Sunnis tend to stress Ali's acceptance and support of their rule, while Shi'a claim that he distanced himself from them, while continuing to serve in the forefront of the Muslim armies.
Shi'a Muslims regard this as yet another instance of the persecution of Muhammad's lineage, the Ahl al-Bayt, at the hands of the caliphs they regard as usurpers.
Abu Bakr gave state pensions to Muhammad's widows, but Muhammad's blood relatives, Ali, Fatimah and Ibn Abbas, did not receive even that much.
Muir says that Ali 'never asserted the leading position', was forgiving of his enemies, always attempting conciliation.
Abu Musa having proclaimed that he deposed both Ali and Mu'awiyah, `Amr declared that he also deposed Ali, but invested Mu'awiyah with the caliphate.
The assassins sent against Mu'awiyan and `Amr failed; the only assassin who succeeded was the one who attacked Ali.
Ali's own account says that he was the 'first ... who responded to the call of Islam.
Ali stood firm in support of Muhammad during the years of persecution of Muslims in Mecca.
The Kharijites departed from Ali's company at the Battle of Siffin, believing that 'God alone should judge' and that he had been wrong to defer to human arbitration.
The Shi'a version of the confession of faith (shahada) also includes an explicit reference to Ali.
Sunni and Shi'a also disagree on Ali's attitudes towards Abu Bakr, and the two caliphs who succeeded him, Umar ibn al-Khattab and Uthman.
Ali's own position was that before he took action against the 'mischief-makers' responsible for Uthman's death, he first needed to strengthen his hold on power.
Shi'a is actually an abbreviation of Shi'at Ali, meaning "the partisans of Ali ."
In 656 C.E., the third caliph Uthman, was murdered in his own house, in Medina, by rebellious Muslim soldiers.
The caliphs who followed Abu Bakr, Umar and Uthman, also refused to return the various properties, whether to Ali or to Muhammad's widows.
Ali had a strong claim to the leadership, both as one of Muhammad's closest assistants and as his cousin and son-in-law, but he was passed over for the leadership.
Ali first distinguished himself as a warrior in 624 C.E., at the Battle of Badr, the first armed conflict in which Muslims were involved.
Mu'awiyah I thus became caliph and established the Umayyad dynasty of caliphs.
The capital of the province of Syria, Damascus, was held by Mu'awiyah, the governor of Syria and a kinsman of Ali's slain predecessor.
Both men, having persuaded Ali to accept office, were now upset that they had not been rewarded governorships; but the stated reason for the revolt was Ali's failure to avenge Uthman's murder.
Ali and Fatima, as well as Muhammad's widows, had an additional cause for disaffection with Abu Bakr.
Mu'awiyah raised an army and marched against Ali, also demanding vengeance for the death of Uthman.
Ali then transferred his capital from Medina to Kufa, the Muslim garrison city founded by Umar in what is now Iraq.
Ali and Muhammad were thus cousins raised as brothers, with Ali in the role of a younger brother, looking up to Muhammad and ready to follow his lead.
The Shi'a believe that the Imam, or leader of the Muslims, who must be a male descendant of Muhammad, possesses special qualities.
Abu Musa Asha'ri was appointed advocate for Ali, and `Amr-ibn-al-As, a veteran diplomat, was for Mu'awiyah.
After Fatima's death, Ali again claimed her inheritance, but was denied with the same argument.
Hasan is, however, revered by most Shi'a as the second imam; his brother Husayn bin Ali is reckoned as the third, except by the Shi'a Ismaili, who consider him the second imam.
The most famous collection of Ali's speeches and letters is the Nahj al-Bal?gha meaning “The Peak of Eloquence,” which Shi'a regard as second only to the Qur'an in importance.
Ali is greatly respected by most Muslims (the Ibadi - which exists in Oman and developed from the Kharijites might be the only dissenters).
Shi'a Muslims see him as the first imam and the first rightful caliph.
Ali was stabbed on the head by a poisoned sword while he was performing morning prayers.
Almost the first act of his caliphate was to put down a rebellion led by Talha and al-Zubayr, who were urged on by Aisha, Muhammad's widow who was also related to them.
At this point, the soldiers of Ali refused to fight any longer, and demanded that the issue be referred to arbitration.
Muir says that Ali 'never asserted the leading position', was forgiving of his enemies, always attempting conciliation.
Ali's descendants by Fatima are known as sharifs, sayyeds, or sayyids.
British historian and orientalist, Thomas Carlyle, in his book On Heroes and Hero Worship and the Heroic in History, calls Ali, "noble-minded...full of affection and fiery daring.
Ali's mother, Fatima bint Asad, also belonged to Banu Hashim, making Ali a descendant of Ishmael, the son of Ibrahim (Abraham).
Ali had eight wives after Fatima's death, but while she was alive he was monogamous.
According to tradition, three Muslim zealots (purists later termed Kharijites) had agreed to assassinate Ali, Mu'awiyah and `Amr, as the authors of disastrous feuds among the faithful.
A splendid mosque called Mashad Ali was afterwards erected near the city at Najaf, the place of his burial (although some believe he is buried at Mazar-e-Sharif in Afghanistan).
Sir William Muir praised Ali's 'forbearance and magnanimity' and his wisdom in counsel but comments that this was 'for other than himself', suggesting that he was a better adviser than leader.
When Muhammad was orphaned and then lost his grandfather, Abu Talib took Muhammad into his house.
Sunni Ali, also known as Sunni Ali Ber, was born Ali Kolon. He reigned from about 1464 to 1492. Sunni Ali was the first king of the Songhai Empire, located in Africa and the 15th ruler of the Sonni dynasty. ... Sunni Ali organized a fleet to patrol the Niger river.