Yom Kippur, also known as Day of Atonement, is the holiest day of the year for the Jews. Its central themes are atonement and repentance. Jews traditionally observe this holy day with a 25-hour period of fasting and intensive prayer, often spending most of the day in synagogue services. Yom Kippur completes the annual period known in Judaism as the High Holy Days (or sometimes “the Days of Awe”).