Havalah is a Jewish religious ceremony that marks the symbolic end of Shabbat and holidays, and ushers in the new week. In Judaism, Shabbat ends -- and the new week begins -- at nightfall on Saturday. Havdalah may be recited as soon as three stars are visible in the night sky. Some communities delay the Havdalah until later, in order to prolong Shabbat. If for some reason one cannot recite Havdalah on Saturday night, it may be observed as late as Tuesday evening.