Islam is a monotheistic religion founded by Muhammad in the 7th century AD. It has five main beliefs: one God called Allah, judgment day, acceptance of prophets including Moses and Jesus, Muhammad as the final prophet, and the Quran as the holy book. The religion spread rapidly from the 7th century onward through conquest and trade, reaching as far as Spain, India, and Russia. Islam split into the Sunni and Shia sects in the 7th century due to disputes over religious leadership. Both made major cultural and scientific contributions to fields like architecture, medicine, mathematics, and geography.