What Is Eid al-Adha? Five Facts About the Muslim Holiday

The world's 1.8 billion Muslim adherents will celebrate Eid al-Adha this week, marking one of Islam's most important holidays.

As of 2017, the U.S. is estimated to be home to nearly 3.5 million Muslims, meaning millions countrywide will be celebrating along with others around the world. Newsweek asked Dr. Ebrahim Moosa, a professor of Islamic Studies at the University of Notre Dame in Indiana, to explain more about the holiday and why it's important to Muslims.

A family picnic in London's Burgess Park during the first day of Eid al-Adha celebrations, on September 1, 2017. Rob Stothard/Getty Images

1. When is Eid al-Adha?

The date for the holiday changes from year to year, as it is scheduled according to the Islamic lunar calendar. It falls annually on the 10th day of Dhul Hijjah (the month of pilgrimage), the twelfth and final month of the Islamic year.

Observance of the holiday is common among all Muslims, but different sects celebrate on slightly different dates. Moosa explained that some Muslims will celebrate this year on Tuesday, August 21, while others will start on Wednesday, August 22. They will continue to celebrate until August 25 or 26, respectively.

2. What is Eid al-Adha?

"Eid al-Adha is the celebration at the culmination of the pilgrimage (hajj) which is an obligation—one of the five pillars of Islam—[for] every Muslim who is able to perform it and afford it," Moosa said.

The pilgrimage, which takes place in Mecca, Saudi Arabia, retraces the footsteps that Muslims believe Prophet Abraham—whom Jews and Christians also revere—his wife Hagar and their son Ishmael took, as well as rituals that are reminders of the "trials and tribulations" faced by the family.

"The Eid is the vicarious celebration of the end of that pillar of Islam which pilgrims complete in Mecca," said Moosa.

3. How do Muslims celebrate?

Muslims who journey to Mecca for the holiday begin their rituals on this day.

"Non-pilgrims, all those at home, celebrate the festival with a feast with the family, and those who can afford it will sacrifice an animal and share the meat with those who are [suffering from poverty], with neighbors and [with] family," Moosa said.

Muslim worshippers perform prayers around the Kaaba, Islam's holiest shrine, at the Grand Mosque in Saudi Arabia's holy city of Mecca on August 15, prior to the start of the annual Hajj pilgrimage. BANDAR AL-DANDANI/AFP/Getty Images

4. Do Muslims fast during the holiday?

While the ritual month of fasting for Muslims is Ramadan, which happened between May and June this year, some believers undertake voluntary fasts for Eid al-Adha.

"In the run-up to Eid and after the day of Eid, Muslims who are not on pilgrimage will do voluntary fasts as a sign of their devotion and respect for the act of pilgrimage, and as a sign of solidarity with their fellow believers on pilgrimage," Moosa said.

5. Why is it important?

The holiday reminds Muslims that they should be willing to sacrifice of themselves for Allah (God). It commemorates the willingness of Abraham to sacrifice his own son at Allah's request. Fortunately, before Abraham went through with killing his son, Allah intervened and gave him a lamb to sacrifice instead.

As a result, Muslims traditionally eat sheep or goat during the holiday.