The fourth of the Ten commandments states: "Remember the day of Shabbat to sanctify it". This means that we should sanctify the Shabbat with words, by beginning and ending Shabbat with a ceremony in which we declare the holiness of Shabbat and its distinction from all other days of the week.
The opening ceremony we make at the initiation of Shabbat is called qiddush (=consecration). And the closing ceremony we do at the end of Shabbat is called habdala (=distinction).
The Rabbis, in this case the anshe keneset hagedola ( Men of the Great Assembly, ca. 450 BCE) instructed us to perform these two ceremonies over a cup of wine.
The Habdala ceremony includes four blessings: 1. A blessing over the wine. 2. A blessing over aromatic spices 3. A blessing over the light of a fire. 4. A blessing in which we state the distinction between holiness (Shabbat) and the ordinary (= ḥol, i.e., weekdays).
Smelling an aromatic spices, according to the some opinions, is a symbolic compensation for the loss of the "additional soul" (neshama yetera) which accompanied us throughout the Shabbat.
The purpose of the blessing over the light "Blessed are You, haShem...the Creator of the light of the fire" - is to show thatmelakha (=an activity forbidden on Shabbat) is now permitted. It also remind us that a new week begins, and the first thing God created in the Creation-week was light (Gen.1:3). When saying the blessing over the light one should actually benefit from the light. The Rabbis said that the light should be intense enough to distinguish, for example, between two similar coins, one from your country and one from another country. The custom is to bring our hand --semi closed-- near the candle, distinguishing between the shadowed area and the lighted area of the hand (light vs. darkness). Some have the custom to look at their fingernails, benefiting from the light which helps to recognize the nails from the fingers.
Candle lighting in NYC: 5:05 pm
Shabbat ends in NYC: 6:03 pm
a Ladino presentation (with Hebrew subtitles).