Considered the most important holiday in the Jewish faith, Yom Kippur is also known as the day of atonement. It begins at sundown on Oct. 8 and ends at nightfall the following day.

The holy day ends the “10 Days of Repentance” in the Jewish calendar that began with Rosh Hasanah, all occurring during the Jewish lunar month of Tishrei. But how did this holy day come about? Here’s everything you need to know about the holiday.

Origins of Yom Kippur

Yom Kippur was first thought to have occurred during the Israelites’ journey from Egypt to the Promised Land under the leadership of Moses.

According to Leviticus, after God had punished Aaron’s sons by setting them on fire in the tabernacle, he called upon Moses and Aaron to conduct a very complicated ceremony including slaughtering multiple animals for the sins of themselves and their people. God commanded that they must perform this ceremony on the 10th day of the seventh month in order to atone for their sins and be cleansed. In that command, he instructed that they must not do any work as it is a day of sabbath rest.

“This is to be a lasting ordinance for you: Atonement is to be made once a year for all the sins of the Israelites,” according to ​Leviticus 16:34​.

Observation of Yom Kippur

According to a survey conducted by the ​Pew Research Center​, more than half of Jews will observe the holiday by fasting, either part of the day or entirely. However, fasting is not the only way Jews observe Yom Kippur. It is common, especially among popular celebrities in New York like Jerry Seinfeld, to give up cars. By giving up cars, they are giving up riding and driving for the entire day. As Yom Kippur is considered to be a Sabbath day of rest, many will avoid work and some attend a religious service at a synagogue.

While according to Leviticus, the way to repent for sins was to sacrifice several animals in the Jewish Temple, that is no longer the case. The fasting, which according to the Torah must occur from the sundown of the evening before Yom Kippur and last until nightfall the next day, is meant to cleanse the body and spirit. In an article for ​Aish.com​, Jewish educator Aliza Bulow wrote, “​Fasting is difficult, but it is the very fact of its difficulty that gives us the opportunity to connect to God in a stronger way. The sublimation of our own desires to eat in favor of the directive to fast is itself an offering.”

As many Jews follow this 25 hours of fasting, there are other restrictions about bathing, washing, sex and wearing makeup or leather shoes. The purpose of these restrictions, like fasting, is to connect with God by taking the focus away from possessions. No matter how someone observes the holiday, the purpose is all the same: to ask for forgiveness for their sins from God and others.

When it comes to the religious services, a mazchor (prayer book) is used to recite specific prayers or special texts. At the end of the service, a shofar (a ram horn) is blown to signify the end of Yom Kippur, and each member fasts.

Pop culture linked to Yom Kippur

Dating back to 1965, Sandy Koufax, a pitcher for the Los Angeles Dodgers, opted out of pitching for the first game of the World Series because it fell on Yom Kippur.

Koufax is not the only Jew who has been in the spotlight for his Jewish practices. Celebrities such as Jerry Seinfeld, Michael J. Fox, Paul Schaffer and Ivanka Trump have all attended synagogue services during Yom Kippur. Whether they fully participate in the holiday by fasting from modern luxuries such as coffee and cars is up for debate.

Other references to Jewish tradition in pop culture can be found in the shows Gossip Girl and the Amazon original The Marvelous Mrs. Maisel. Both of these programs devoted an entire episode to Yom Kippur. Each episode revealed the significance of the holiday while also poking fun at the characters’ inability to make it through the 26 hours of fasting.

Episode seven of The Marvelous Mrs. Maisel, titled Look, She Made a Hat, features not only the breakfast but the religious service that takes place before. A scene in the synagogue is a comical look at a Yom Kippur service, including fasting jokes and the long-awaited blowing of the shofar, after which everyone pours out of the temple scrambling for snacks or nuts from purses.

Callie Patteson and Sydney Powell are students at The King’s College in New York City.