Religious practices include the Five Pillars of Islam, which are five duties that unite Muslims into a community.[5] Islamic law (Arabic: ????? Šari-?ah) touches on virtually every aspect of life and society, encompassing everything from dietary laws and banking to warfare and welfare.[6] Almost all Muslims belong to one of two major denominations, the Sunni (85%) and Shi'a (15%). Islam is the predominant religion in much of Africa, the Middle East, as well as in major parts of Asia.[7] Large communities are also found in China, Russia and the Balkans. Converts and immigrant communities are found in almost every part of the world. About 20% of Muslims live in Arab countries,[8] 30% in the Indian Subcontinent, and 15.6% in Indonesia alone, the largest Muslim country in absolute numbers.[9] With 1.3 billion to 1.8 billion Muslims, Islam is the second-largest religion in the world and the fastest growing religion in the world.[10][11]

Born in 570 CE in the Arabian city of Mecca,[11] he was orphaned at a young age and brought up under the care of his uncle Abu Talib. He later worked mostly as a merchant, as well as a shepherd, and was first married by age 25. Discontented with life in Mecca, he retreated to a cave in the surrounding mountains for meditation and reflection. According to Islamic beliefs it was here, at age 40, in the month of Ramadan, where he received his first revelation from God. Three years after this event Muhammad started preaching these revelations publicly, proclaiming that "God is One", that complete "surrender" to Him (lit. isla-m) is the only way (di-n)[12] acceptable to God, and that he himself was a prophet and messenger of God, in the same vein as other Islamic prophets.[9][13][14]

Muhammad gained few followers early on, and was met with hostility from some Meccan tribes; he and his followers were treated harshly. To escape persecution Muhammad and his followers migrated to Medina (then known as Yathrib) in the year 622 CE. This event, the Hijra, marks the beginning of the Islamic calendar. In Medina, Muhammad united the conflicting tribes, and after eight years of fighting with the Meccan tribes, his followers, who by then had grown to ten thousand, conquered Mecca. In 632, a few months after returning to Medina from his Farewell pilgrimage, Muhammad fell ill and died. By the time of his death, most of the Arabian Peninsula had converted to Islam; and he united the tribes of Arabia into a single Muslim religious polity.[15][16]

The revelations (or Ayat, lit. "Signs of God")—which Muhammad reported receiving until his death—form the verses of the Qur'an, regarded by Muslims as the “Word of God” and around which the religion is based. Besides the Qur'an, Muhammad’s life (sira) and traditions (sunnah) are also upheld by Muslims. They discuss Muhammad and other prophets of Islam with reverence, adding the phrase peace be upon him whenever their names are mentioned.[17] While conceptions of Muhammad in medieval Christendom and premodern times were largely negative, appraisals in modern times have been far less so.[14][18] Besides this, his life and deeds have been debated by followers and opponents over the centuries.[19]