Islam (Arabic: الإسلام; al-'islām) is a monotheistic, Abrahamic religion originating with the teachings of the Islamic prophet Muhammad. The word Islam means "submission", or the total surrender of oneself to God (Arabic: الله‎, Allāh). An adherent of Islam is known as a Muslim, meaning "one who submits [to God]". The word Muslim is the participle of the same verb of which Islām is the infinitive. There are between 1 billion and 1.8 billion Muslims, making Islam the second-largest religion in the world.

Muslims believe that God revealed the Qur'an to Muhammad, God's final prophet, through the angel Gabriel, and regard the Qur'an and the Sunnah (words and deeds of Muhammad) as the fundamental sources of Islam. They do not regard Muhammad as the founder of a new religion, but as the restorer of the original monotheistic faith of Abraham, Moses, Jesus, and other prophets.

Islam includes many religious practices. Adherents are required to observe the Five Pillars of Islam, which are five duties that unite Muslims into a community. In addition to the Five Pillars, Islamic law (sharia) has developed a tradition of rulings that touch on virtually all aspects of life and society.