Distinguishing Shabbat from the week
Havdalah marks the end of Shabbat. It is a beautiful ritual. We make blessings over a cup of wine, a plaited candle whose flames flare up like a torch, and a box filled with spices.
There is something to stimulate each of the sentences. (Touch you ask? The warmth of the flame. Hearing? The sound of the blessings and verses.)
According to tradition, the spices are to revive us as the "extra soul" that enters us for the duration of Shabbat leaves for another six days. Lighting the plaited candle marks the creation and discovery of fire, immediately after the first Shabbat of creation.
The word havdalah means separation. Havdalah and kiddush serve as bookends at the opening and closing of Shabbat (Maimonides, Hilchot Shabbat, Chapter 29). They distinguish between the working week and the rest and peace of Shabbat, demarcating an island of holy time.