Why are there two main branches (groups) of believers in Islam (Sunni and Shia)?

Though the two main sects within Islam, Sunni and Shia, agree on most of the fundamental beliefs and practices of Islam, a bitter split between the two goes back some 14 centuries. The divide originated with a dispute over who should succeed the Prophet Muhammad as leader of the Islamic faith he introduced.

Explanation:

answer; the above statement is (false);

answer; ratification;