Caliph (From the Arab Word Khalifa, Deputy, Successor)
CALIPH (from the Arab word khalifa, deputy, successor)
Muslim ruler and head of the Muslim community. The first Caliphs and successors to Muhammad were Abu Bakr al-Siddiq (632–635), Omar ibn al-Khattab (635–644), Othman ibn Affan (645–656), and Ali ibn Abi Talib (656–661). Some Muslim historians question the claim of Abu Bakr to the title of Caliph, since it was not until the reign of Omar ibn al-Khattab that the "commander of believers" was designated by the title of khalifat rasûl Allâh (successor to God's messenger). The Caliphate has been in dispute throughout history, with multiple claims to authority. Therefore, historians distinguish between the Eastern Caliphate, the Umayyad Caliphate of Cordoba, the Fatimid Caliphate of North Africa, and the Ottoman Caliphate.