Israel observes 10 major holidays drawn from the Jewish religious calendar and national commemorations. Yom Kippur is the most solemn day, when the entire country comes to a standstill. Rosh Hashana, Passover, Sukkot, and Shavuot are the principal religious festivals. Holocaust Remembrance Day and Independence Day form a powerful emotional sequence from mourning to celebration. Hebrew calendar dates shift annually relative to the Gregorian calendar, so holiday dates vary each year.