Rosh Hashanah is the Jewish new year and known as one of the holiest days of the year. It is celebrated with a festival that begins on the first day of Tishrei, the seventh month of the Hebrew calendar, which usually falls during September or October. Rosh Hashanah commemorates the creation of the world and marks the beginning of the Days of Awe, a 10-day period of introspection and repentance that culminates in the Yom Kippur holiday, also known as the Day of Atonement.