Islam 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. An adherent of Islam is known as a Muslim, meaning “one who submits [to God].” There are between 1 billion and 1.8 billion Muslims, making Islam the second-largest religion in the world, after Christianity.

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.

Islam includes many religious practices. Adherents are generally required to observe the Five Pillars of Islam. 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. This tradition encompasses everything from practical matters like dietary laws and banking to warfare and welfare. Almost all Muslims belong to one of two major denominations, the Sunni (85%) and Shi'a (15%).

Of the total world Muslim population, about 20% live in the Arab countries (where Muslims comprise majority populations, with Christian and other religious minorities of differing sizes by country), 30% in the countries of the Indian subcontinent, and 15.6% in Indonesia alone, which is the largest Muslim country in absolute numbers.

- From Wikipedia