Over which main point did Sunnis and Shias disagree

The main point of disagreement between Sunnis and Shias is the issue of who should be the rightful successor to the Prophet Muhammad as the leader of the Muslim community. Sunnis believe that the successor should be elected by the community, while Shias believe that the successor should be a direct descendant of the Prophet Muhammad through his daughter Fatimah and her husband Ali. This led to the split between the two sects following the death of the Prophet Muhammad in 632.