The Hebrew calendar or Jewish calendar is the calendar used in Judaism. It is used to set the dates of the Jewish holidays and the weekly public reading of the Torah. It is used to set the date for a Bar Mitzvah or Bat Mitzvah, the day a young person is considered an adult in Judaism. It sets the "Yahrzeit," the anniversary of the death of a relative. The daily Jewish prayer service changes depending on the day of the Hebrew calendar.