Just before Shabbat begins, two candles are lit marking the division between light and darkness described in the story of Creation and a blessing is recited, generally by the matriarch of the house.
Some say the candles represent the two commandments to “remember” and “observe” Shabbat.
It is customary for Shabbat candles to be lit approximately 20 minutes before sundown on Friday evening, although it is permissible to light them even earlier. This is often done during the summer, when the days are long. The candles may no longer be lit once the sun has set.
Jewish rituals generally require the blessing to be recited before the mitzvah is performed, but not so with candle-lighting – in this case, the candles should be lit first and the benediction recited after, due to the prohibition of lighting a flame after Shabbat has begun.
The matriarch of the house, or whoever is reciting the benediction, customarily closes her eyes or covers them with her hands while saying, "Blessed art Thou, Lord our God, King of the universe, who has sanctified us with His commandments and commanded us to kindle the Sabbath lights."
It is said that, upon opening one's eyes, the sight of the Shabbat candles elicits delight – and that that is regarded as the culmination of the mitzvah.