Faryal M. Khatri of the Islamic Society of North America tells Refinery29 that this holiday pays tribute to one of the greatest demonstrations of faith within Islam: the prophet Ibrahim's willingness to sacrifice his own son at God's command. Ibrahim didn't actually go through with his sacrifice — the story goes that an angel intervened and gave him an animal to sacrifice instead.
The most traditional way to celebrate Eid al-Adha, and emulate Ibrahim's strength of faith, is to sacrifice a goat or a sheep to God. One third of the animal's meat is eaten by the family who kills it, another third is shared among friends and relatives, and the remaining portion is donated to the hungry. Khatri says that, nowadays, some Muslim communities may forego slaughtering an animal altogether and donate to a charity that will do it in their name. These organizations will then distribute meat to the hungry, she explains.
Many Muslims will attend special prayer services and sermons to observe Eid al-Adha. Those who weren't able to attend the Hajj (and cannot pray in person at Mount Arafat) are encouraged to fast the day before Eid al-Adha begins, which is known as the Day of Arafat. "As Prophet Muhammad (Peace be upon him) said," says Khatri, "'Fasting on the Day of 'Arafah absolves the sins for two years: the previous year and the coming year.'"
Eid al-Adha brings the Hajj to a solemn and humbling end, reminding Muslims of the importance of their faith and how they can live out their commitment to God in their regular lives.