Ali ibn Abi Talib (Arabic: عَلِيّ ٱبْن أَبِي طَالِب, ʿAlī ibn ʾAbī Ṭālib; 13 September 601 – 29 January 661) was a cousin and son-in-law of the Islamic prophet Muhammad, who ruled as the fourth caliph from 656 to 661. He is one of the central figures in Shia Islam and is regarded as the rightful immediate successor to Muhammad as an Imam by Shia Muslims.
Ali was born inside the Kaaba in Mecca, the holiest place in Islam, to Abu Talib and Fatimah bint Asad. He was the first male who accepted Islam under Muhammad's watch. Ali protected Muhammad from an early age, and took part in almost all the battles fought by the nascent Muslim community. After migrating to Medina, he married Muhammad's daughter Fatimah, and after her death, he had other wives, including Muhammad's granddaughter Umamah bint Zaynab. He was appointed caliph by Muhammad's companions in 656, after Caliph Uthman ibn Affan was assassinated. Ali's reign saw civil wars and in 661, he was attacked and assassinated by a Kharijite while praying in the Great Mosque of Kufa.Ali is important to both Shias and Sunnis, politically and spiritually. The numerous biographical sources about Ali are often biased according to sectarian lines, but they agree that he was a pious Muslim, devoted to the cause of Islam and a just ruler in accordance with the Qur'an and the Sunnah. While Sunnis consider Ali the fourth Rashidun Caliph, Shia Muslims regard Ali as the first Caliph and Imam after Muhammad. Shia Muslims also believe that Ali and the other Shia Imams, all of whom are from the House of Muhammad's, known as the Ahl al-Bayt, are the rightful successors to Muhammad.