Yom Kippur, the Day of Atonement for those who practice Judaism, is the most important day of the year on the Jewish calendar.
It takes place on the 10th day of Tishri, the first Jewish month, ending the 10-day period of repentance and reflection known as the "High Holidays," which began with Rosh Hashanah.
This year, the solemn holiday begins on the evening of Sunday, Sept. 24 and doesn't come to an end until the following evening.
Typically celebrated with a day of reflection, prayer and fasting, Yom Kippur officially gets underway at sundown, which is 6:25 p.m. in Chicago.
Followers of the Jewish faith attend religious services and do not eat from sundown to sundown. Young children and people who would be facing a medical risk from fasting are exempt.
The fast on Yom Kippur goes for about 25 hours, and during that time followers of the Jewish faith are not allowed to eat or drink anything, including water. Fasting ends at sunset on Monday, which will take place at 7:24 p.m. in Chicago.
When the Day of Atonement is over, a "shofar" horn is blown to mark the end of the fast and a festive meal is prepared to break the fast and rebuild people's strength.
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