The religion represented by a star and crescent is Islam. The star and crescent symbol has been used by Muslims since the Ottoman Empire, and is now a widely-recognized symbol of Islam. It is most commonly used on flags, mosques, and other religious buildings, and is also found in other forms of art and decoration. The star and crescent is sometimes interpreted to represent the five pillars of Islam, the four caliphs who succeeded Muhammad, or the unity of God and the Prophet Muhammad.