Islam - Sunni is a part of the Islam religion. Sunni and Shia Muslims share many fundamental Islamic beliefs but differ over the question of leadership. Sunni Muslims are those who, at Muhammad's death, agreed that the new leader should be chosen from among the Prophet's followers. Abu Bakr, Muhammad's close friend and advisor was chosen as the first Caliph of the Islamic nation. The word "Sunni" in Arabic means "one who follows the traditions of the Prophet".