What divided the Sunni and the Shiite?

The division between Sunni and Shiite Muslims originated from a disagreement over who should succeed the Prophet Muhammad as the leader of the Muslim community. Sunnis believed that leadership should follow community consensus, leading to the election of Abu Bakr as the first caliph, while Shiites believed that leadership should stay within the Prophet's family, leading to the belief in Ali, Muhammad's cousin and son-in-law, as his rightful successor. This difference in opinion resulted in a lasting schism in Islam.