A caliph is the head of a Muslim state governed by sharia, under which ideally the whole ummah—the worldwide Muslim community—is politically united. Such a state ruled by a caliph is known as a caliphate. Muhammad’s followers established the first caliphate to carry on the political system created by the Prophet. There have been numerous caliphates throughout history, the last of which—the Ottoman Dynasty—was abolished in 1924; few have actually encompassed the full ummah. Sunni Muslims generally view a caliph as an elected head of state chosen by the ummah, though historically the office of caliph was often hereditary. Shi’a Muslims believe a caliph must be a divinely-appointed imam descended from the family of Muhammad. There is debate in the Muslim community today on the feasibility of, and the Qur’anic mandate for, a caliph.
The concept of a caliph and caliphate has had a great influence on the religiopolitical history of Islamic civilization. The Muslim world has had a caliph—and, at times, multiple caliphs—for all its history except for less than the last hundred years, when nation-states overtook multinational empires as the primary political unit across the globe. Islamic civilization, culture, and theology came to fruition under the caliphates. The idea of a caliphate means different things to different people: pro-democracy activists point to the requirement in Sunni Islam for an elected caliph who is held accountable to the rule of law; however, the establishment of a caliphate is a common goal among militant Islamist groups, who seek to destroy non-Muslims and their cultures to achieve that end, a fact that has made most moderate Muslims uneasy about the thought of a new caliphate. At the political level, Muslim leaders do not consider the reestablishment of a caliphate to be an urgent goal.