Ramadan, an important Islamic holiday when Muslims fast each day for almost a month, begins this weekend. Here's what to know about the religious holiday.

Ramadan is the ninth month of the Islamic, or Hijri, calendar. Muslims believe that God revealed the first verses of the Quran to the Prophet Muhammad through the Angel Gabriel during Ramadan.

According to Crescent Moon Watch (PDF), a moon tracker run by the United Kingdom’s Nautical Almanac Office, Ramadan’s new moon will begin on February 28 at 3:45am Mecca time (00:45 GMT).

Ramadan commences when a small sliver of the moon, known in astronomical terms as the “waxing crescent,” emerges and becomes visible. And that’s true across the Islamic world.

Ramadan takes place historically during the ninth month of the Islamic Lunar Calendar with this year’s edition starting on February 28.

Ramadan is based on the lunar calendar, which consists of a 12-month year of approximately 354 days. This means each lunar month moves 11 days in the Gregorian calendar observed by the United States.

Stock photo of hanging lights during Ramadan. Getty In correspondence with the first appearance of the crescent moon, Ramadan starts at sundown on March 10 and lasts through April 8 in the United ...