Muhammad (also spelled Mohammed) is regarded as the last and truest prophet in Islam. When Muslim people refer to the Prophet, they are referring to Muhammad. They may also write the phrase, "Peace be upon him," or the abbreviated "PBUH" after his name as a sign of respect. Though Islamic tradition holds that God sent many prophets to mankind, including Jesus and Moses, Muhammad is believed to be the prophet who related the most accurate message of God.
When he was forty years old, Muhammad went into a cave to pray, as he sometimes liked to do so as to avoid distraction. On this day, the angel Gabriel was sent by God to relate a message to Muhammad. Muhammad memorized this message and wrote it down as the Muslim holy book- the Qu'ran or Koran. Muhammad went on to preach this message from God and founded the religion of Islam.