Islam (; Arabic: ٱلْإِسْلَام, romanized: al-Islām [alʔɪsˈlaːm] (listen)) is an Abrahamic, monotheistic religion teaching that there is only one God (Allah), and that Muhammad is a messenger of God. It is the world's second-largest religion with over 1.8 billion followers or 24% of the world's population, commonly known as Muslims. Muslims make up a majority of the population in 50 countries. Islam teaches that God is merciful, all-powerful, and unique, and has guided mankind through prophets, revealed scriptures and natural signs. The primary scriptures of Islam are the Quran, claimed to be the verbatim word of God, and the teachings and normative examples (called the sunnah, composed of accounts called hadith) of Muhammad (c. 570 – 8 June 632 CE).
Islamic scripture claims Islam to be the complete and universal version of a primordial faith that was revealed many times before through prophets including Adam, Abraham, Moses and Jesus, and the Quran in its Arabic to be the unaltered and final revelation of God. Like other Abrahamic religions, Islam also teaches a final judgment with the righteous rewarded paradise and unrighteous punished in hell. Religious concepts and practices include the Five Pillars of Islam, which are obligatory acts of worship, and following Islamic law (sharia), which touches on virtually every aspect of life and society, from banking and welfare to women and the environment. The cities of Mecca, Medina and Jerusalem are home to the three holiest sites in Islam.
Aside from the theological narrative, Islam is historically believed to have originated in the early 7th century CE in Mecca, and by the 8th century the Umayyad Caliphate extended from Iberia in the west to the Indus River in the east. The Islamic Golden Age refers to the period traditionally dated from the 8th century to the 13th century, during the Abbasid Caliphate, when much of the historically Muslim world was experiencing a scientific, economic and cultural flourishing. The spread of Islam has involved conquest by various states and dynasties such as the Islamic Gunpowders, conversion to Islam by missionary activities (dawah) trade.
Most Muslims are of one of two denominations; Sunni (75–90%) or Shia (10-20%). About 13% of Muslims live in Indonesia, the largest Muslim-majority country; 31% of Muslims live in South Asia, the largest population of Muslims in the world; 20% in the Middle East–North Africa region, where it is the dominant religion; and 15% in Sub-Saharan Africa. Sizeable Muslim communities are also found in the Americas, the Caucasus, Central Asia, China, Europe, Mainland Southeast Asia, the Philippines, and Russia. Islam is the fastest-growing major religion in the world.