What happened on the original Yom Kippur?
Yom Kippur is not a commemoration of an event. It is a day of
fasting, reflection, and prayer for forgiveness for the sins of the
past year. The Torah set the date for Yom Kippur on the tenth of
Tishrei in the Jewish calendar. According to the Gregorian
calendar, Yom Kippur falls in September or October.