Eid al-Adha, or the Festival of Sacrifice, is a major Islamic holiday celebrated worldwide. During Eid al-Adha, Muslims worldwide gather for communal prayers, engage in acts of charity, and sacrifice an animal, typically a sheep.On the Day of Arafat, Muslim pilgrims performing the Hajj gather on the plains of Arafat, located outside Mecca.While the holiday falls on the 10th day of Dhu al-Hijjah, the 12th and final month of the Islamic calendar, the exact date of the holiday varies from year to year and is determined by the sighting of the new moon.Hajj, the annual pilgrimage to the holy city of Mecca in Saudi Arabia, also takes place during the Islamic month of Dhu al-Hijjah.The pilgrimage – which is expected to begin on June 26 – takes place from the 8th to the 12th day of Dhu al-Hijjah, with Eid al-Adha falling on the 10th day of the month.The dates are subject to change pending an official announcement by Saudi Arabia’s moon sighting committee in the days leading up to the Hajj and Eid al-Adha.