Islam is a monotheistic religion based on the teachings of the Qur’an. People who follow Islam are called Muslims. They believe that the Qur'an is the word of God (Allah), revealed to the last prophet, Muhammad. Centered in Mecca, Islam is the world's fastest growing religion.
From the time of Muhammad until 1924, successive caliphates were held by various dynasties, including the Rashidun (the first four caliphs after Muhammad), the Umayyads, the Abbasids, the Fatimids, and the Turkish Ottomans.