The next upcoming Yom Kippur starts on sundown of September 15 ending at sundown on Thursday September 16th, 2021.
Considered the holiest day of the year for the Jewish people, activities on Yom Kippur involve prayer and fasting. It centers around atonement and repentance. Fasting begins on the evening before and lasts 25 hours. Most of the time is spent in the synagogue. It is believed that a New Year is granted to those who repent from their sins. Breaking of the fast includes a Havdalah ceremony and taking part of a festive meal afterwards.
Yom Kippur originated with the ritual purification from any impurities that might have occurred the past year in the Temple of Jerusalem. The high priest, the Kohen Gadol, enters the Holy of Holies (the center of the temple) on Yom Kippur. Rituals are carried out to make sure the high priest did not bring in impurities into the Holy of Holies. It was important that he was spiritually and physically pure.