Both sects are Muslim. They believe the Koran is the direct word of God, passed down to the prophet Muhammad in a series of revelations before his death. They pray in the direction of Mecca, and share the same dietary and general social restrictions.
Their schism lies in disputes over who would succeed Muhammad as leader of the faithful after his death in 632. The Shiites thought the prophet’s son-in-law and cousin should lead as caliph, particularly given his blood relationship to Muhammad. Their opponents, the Sunnis, thought Abu Bakr, one of Mohammad’s first converts, should be their leader.
The Shiites lost a series of wars for power in the early years of Islam and today are the clear minority in global Islam, making up about 15 percent of adherents. They are in the majority in Iraq and Iran.