Yom Kippur is the most sacred day of the Jewish calendar--The Day of Atonement. Jewish people fast on Yom Kippur and spend most of the day in prayer. It is on Yom Kippur that you repent for your sins and seek forgiveness for sins against G-d and against man.
G'mar chatimah tovah! to all those observing Yom Kippur. ( “May you be sealed for a good year in the Book of Life.”)