This is an updated version of an article originally published on May 26, 2017.

Ramadan is a month of fasting many Muslims observe to commemorate the first revelation of the Quran to the Prophet Muhammad, according to Islamic history.

What are the dates of Ramadan?

Because the cycle of the lunar calendar does not match the solar calendar, the dates of Ramadan shift by approximately 11 days each year. In 2019, Ramadan is expected to begin in the evening on Monday, May 6 , in the United States, although the date is only confirmed once the moon is sighted.

The end of Ramadan is marked by the holiday of Eid al-Fitr, which takes place either 29 or 30 days after the beginning of the month. On Eid al-Fitr, morning prayers are followed by feasting and celebration among family and friends.