Yom Kippur in 2023 begins at sundown on Sunday, September 24th and ends at sundown on Monday, September 25th. It is observed as a day of fasting and prayer in the Jewish faith. Yom Kippur is the holiest day of the year for Jews, known as the Day of Atonement, occurring on the 10th day of the Hebrew month of Tishrei. The holiday lasts approximately 25 hours, starting the evening before the calendar date until the evening of the day itself.