Yom Kippur is the most solemn day in the Jewish calendar. It means Day of Atonement and Jews don't eat or drink for 25 hours. It's a day to reflect on the past year and ask God's forgiveness for any sins.
It comes ten days after Rosh Hashanah, the New Year, and is the chance for a new beginning.
The 'shofar' or ram's horn is blown at the end of Yom Kippur which signals the end of the ten-days of High Holy Days in the Jewish calendar.
A big family meal is eaten before the fast starts.