Which led to the division between Sunni and Shia following the death of Muhammad?

The division between Sunni and Shia Islam emerged after the death of the Prophet Muhammad in 632 CE, primarily over the issue of leadership. Sunnis believed that the community should choose the leader (Caliph), supporting Abu Bakr, a close companion of Muhammad. In contrast, Shia Muslims believed that leadership should remain within Muhammad's family, specifically designating Ali, his cousin and son-in-law, as the rightful successor. This disagreement over succession and authority laid the foundation for the enduring split between the two sects.