Ramadan, in Islam, the ninth month of the Muslim year, during which all Muslims must fast during the daylight hours. Indulgence of any sort is forbidden during the fast. There are only a few who are exempt, e.g., soldiers, the sick, and the young. Because of the purely lunar calendar, Ramadan falls in different seasons. The final day of Ramadan, Id al-Fitr, is celebrated by a day of feasting. The first revelation of the Qur'an is commemorated in this month.