Adherents of Islam constitute the world's second largest religious group. According to a study in 2015, Islam has 1.8 billion adherents, making up about 24.1% of the world population. Most Muslims are either of two denominations: Sunni (87–90%, roughly 1.6 billion people) or Shia (10-13%, roughly 180–230 million people). Islam is the dominant religion in Central Asia, Indonesia, Middle East, North Africa, the Sahel and some other parts of Asia. The diverse Asia-Pacific region contains the highest number of Muslims in the world, easily surpassing the Middle East and North Africa.
South Asia contains the largest population of Muslims in the world. One-third of Muslims are of South Asian origin. Pakistan is the second largest Muslim-majority country in terms of population in the world. Islam is the dominant religion in the Maldives, Afghanistan, and Bangladesh. India is the country with the largest Muslim population outside Muslim-majority countries with about 200 million adherents.
The various Hamito-Semitic, Arab, Berber, Turkic, and Iranic countries of the greater Middle East-North Africa (MENA) region, where Islam is the dominant religion in every country other than Israel, host 23% of the world's Muslims.
The country with the single largest population of Muslims is Indonesia in Southeast Asia, which on its own hosts 13% of the world's Muslims. Together, the Muslims in the countries of Southeast Asia constitute the world's third-largest population of Muslims. In the countries of the Malay Archipelago, Muslims are majorities in each country other than the Philippines, Singapore, and East Timor.