The Prophet Muhammad was in a cave on Mount Hira, close to Mecca, when the angel Gabriel appeared and revealed the first five lines of Surh Al-Alaq (chapter 96 of the Qur’an).
Following this first revelation, Muhammad received many revelations of holy text for the rest of his life ( a further twenty three years).
The revelations were recorded by scribes and after the death of Muhammad, they compiled them in texts. The version of these texts that became the Qur’an was established by Caliph Uthman.