Sunni Islam is the largest branch of Islam and the largest religious denomination in the world. It holds that Muhammad did not appoint any successor and that his closest companion Abu Bakr (r. 632–634) rightfully succeeded him as the caliph of the Muslim community, being appointed at the meeting of Saqifa. This contrasts with the Shia view, which holds that Muhammad appointed Ali ibn Abi Talib (r. 656–661) as his successor. Nevertheless, Sunnis revere Ali, along with Abu Bakr, Umar (r. 634–644) and Uthman (r. 644–656) as 'rightly-guided caliphs'.
The term Sunni means those who observe the sunna, the practices of Muhammad. The Quran, together with hadith (especially the Six Books) and ijma (scholarly consensus), form the basis of all traditional jurisprudence within Sunni Islam. Sharia legal rulings are derived from these basic sources, in conjunction with consideration of public welfare and juristic discretion, using the principles of jurisprudence developed by the four legal schools: Hanafi, Hanbali, Maliki and Shafi'i.
