The Day of Atonement (or Repentance) is observed on the tenth day of the month of Tishrei in the Hebrew calendar, which usually falls between mid-September and mid-October in the Gregorian calendar.

It marks the end of the ten-day period known as the High Holy Days, (also referred to as Yamim Noraim or Days of Awe) that begin with the Jewish New Year, Rosh Hashanna.

Yom Kippur is considered the ideal time in the Jewish calendar to repent and start the new year cleansed of sin.