Muslims celebrate the birth of Prophet Muhammad, who is considered the last and most important of the prophets in Islam. They celebrate his birth on the twelfth day of the month of Rabi' al-awwal, which usually falls in March or April in the Gregorian calendar. Muslims also celebrate other festivals such as Eid al-Fitr, which marks the end of Ramadan, and Eid al-Adha, which commemorates the story of Abraham's sacrifice.