Eid Al Adha is one of the holiest celebrations on the Islamic calendar. The holiday known as the Feast of Sacrifice represents the end of Hajj, an annual Islamic pilgrimage to Mecca in Saudi Arabia that lasts three to four days. The Koran recommends all Muslims make the journey at least once in their lifetime.

What is Eid Al Adha?

Muslims celebrate this day as a reminder of the time in which Ibrahim was about to sacrifice his son but was told by God to sacrifice an animal instead. The celebration symbolizes Ibrahim’s devotion to Allah.

When will Eid Al Adha start?

Up to 2 million Muslims from around the world arrived in Saudi Arabia for the start of Hajj this week. The start of Eid Al Adha is determined based on the lunar cycle, which means the festival falls on a different date every year. In 2016, it was expected to fall on Sunday. But the new moon was not spotted on Sept. 1 as expected and instead was spotted on the second day of the month. That means Eid Al Adha will start on Monday and end Tuesday, Metro UK reported.

How is Eid Al Adha celebrated?

Depending on where you are in the world, Eid Al Adha could be celebrated on a different day. For example, the Saudi Arabia’s Supreme Court announced that it would celebrate the festival Monday, whereas other nations will celebrate Tuesday.

Muslims start out the day with a morning prayer, then exchange gifts and food among family and friends. They are required to share their food and money with the poor so they can also take part in the celebrations. Worshippers typically slaughter an animal like a goat or sheep. Close to 10 million animals are slaughtered in Pakistan on Eid.

For those who make the pilgrimage to Saudi Arabia, they are expected to perform two rituals. The first is a lesser pilgrimage known as “Umrah,” or a journey to Mecca at any time of the year. The second is the main pilgrimage, known as “Hajj.” During these rituals, worshippers are to circle the Kaaba, believed to be a shrine built by Ibrahim and pray to Allah.

The festival is traditionally four days long, but the celebration of the public holiday varies depending on the country.