Sunni Islam is the largest denomination of Islam, comprising about 85 percent of the world’s over 1.5 billion Muslims. In contrast to the Shi'a, Sunnis see Islam as continuous with the teachings of Muhammad and his first four successors, the "rightly guided caliphs." (For Shi'a Muslims, the valid line of succession ran through Muhammad's relatives). Sunni Islam accepts a wide variety of hadith—accounts of the sayings and actions of the Prophet—as authoritative, and acknowledges the legitimacy of diverse schools of Islamic law (sharia) that govern proper roles and relationships in the family and society. In keeping with this internal diversity, Sunni Islam has no clear hierarchical structure. It emphasizes the direct relationship between the believer and God.
As the denomination of the vast majority of the world’s Muslims, Sunni Islam has shaped a large number of world cultures and has created a sense of global Muslim community (ummah) among peoples spanning from West Africa to Indonesia. Divergent currents of Sunni Islam extend from the spiritual and mystical Sufi tradition to the stricter Salafi or Wahhabi tradition most firmly established in Saudi Arabia. Historically, Sunni Islam has thrived amid a wide variety of political regimes; the lack of a hierarchical clerical structure and diverse approaches to sharia have militated against the formation of theocracy.