A caliph is a religious and political leader in the Islamic community, known as the Ummah. The title means "successor" or "representative," and the caliph is considered a successor to the Prophet Muhammad. Historically, caliphs have played a crucial role in guiding the Muslim world and implementing Islamic law. The caliphate, the system of governance led by a caliph, has existed in various forms since the early days of Islam. Notable caliphates include the Rashidun, Umayyad, and Abbasid caliphates, each contributing to the spread of Islam and the development of Islamic culture and civilization.