Who was Ali ibn Abi Talib?
The two main denominations of Islam are the Sunni and Shia sects. They differ primarily upon of how the life of the ummah ("faithful") should be governed, and the role of the imam. These two main differences stem from the understanding of which hadith are to interpret the Quran. Sunnis believe the true political successor of the Prophet in Sunnah is based on ٍShura (consultation) at the Saqifah which selected Abu Bakr, father of the Prophet's favourite wife, 'A'ishah, to lead the Islamic community while the religious succession ceased to exist on account of finality of Prophethood. Shia on the other hand believe that the true political as well as religious successor is Ali ibn Abi Talib, husband of the Prophet's daughter Fatimah (designated by the Prophet).