Most Muslims determine the beginning and end of the month of Ramadan by the sight of the first crescent of the ninth new moon of the lunar year. The calculated time of the new moon can also be used, and some Muslims use Saudi Arabia's official declaration to mark Ramadan.
Ramadan is the ninth month of the Islamic calendar. Because the Islamic calendar is based on the lunar cycle, months begin when the first crescent of a new moon is seen. The Islamic year is 10 to 11 days shorter than the Western calendar year, and the dates of Ramadan vary from year to year.