son of Abu Talib (son of Abdul Muttalib) and Fatima (daughter of Asad). Abu Talib was an older brother of Muhammad's father Abdallah. He took care of Muhammad when he was young. Ali married the youngest daughter of Muhammad, Fatima. Thus, Ali is a cousin and son-in-law of Muhammad. He became the 4th caliph (656-661 A.D.), after the murder of the third caliph Uthman.
Ali became a Muslim when he was 10 years old. The hadiths contain many stories about Muhammad's fondness and special consideration for Ali, although sometimes it is difficult to tell if these are fabricated by the his proponents, or whether they were genuine. Nevertheless, some of these hadiths belong to the Sunnis. After Muhammad's death, a group of Muslims supported Ali to be the caliph, but the rest chose Abu Bakr. Those who supported Ali came to be known as the Shi'ites.
Ali was supposed to have kept a codex of the Qur'an in chronological order instead of the order found in today's Qur'an. He was also credited with gathering the Qur'an together before Uthman, although the hadith is isolate. For more details, see Collection of the Qur'an - from the hadiths.
The capital of Ali's administration was moved to Iraq. Muawiya, the governor of Syria, rebelled against Ali, but after the inconclusive battle Ali and Muwaiya had a truce. In 40 A.H., the Kharijites, who broke away from Ali because of the truce, wanted the caliphate to end, insisting to be ruled over by no ruler except God. Ali was assassinated in 661 A.D. He was stabbed to death with a poisoned sword by ibn Muljim, on 20th Ramadan, 40. A.H.. Shiites believed him to be the first imam.