Havdalah 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.
Havdalah is normally recited over kosher wine or kosher grape juice, although other beverages (except for water) may be used if wine or grape juice is not available. On completion of the Shabbat, a special Havdalah candle braided with more than one wick is lit, a prayer is recited, and it is customary to gaze at one's fingernails reflecting the light of the candle. Spices, often stored in a decorative container, are handed around so that everyone can smell the fragrance.
Havdalah is intended to require a person to use all five senses. Taste the wine, smell the spices, see the flame of the candle and feel its heat, and hear the blessings.
According to some customs, at the conclusion of Havdalah, the leftover wine is poured into a small dish and the candle is extinguished in it, as a sign that the candle was lit solely for the mitzvah of Havdalah. Based on Psalms 19:9, "the commandment of the Lord is clear, enlightening the eyes," some Jews dip a finger into the leftover wine and touch their eyes or pockets with it. Because it was used for a mitzvah, the wine is considered a "segulah," or good omen.