Shabbat is the Jewish day of rest and celebration that begins on Friday at sunset and ends on the following evening after nightfall. Here are some links to learn more about Shabbat (or Shabbos, as it is sometimes called):

What Is Shabbat?
What to Expect at Shabbat Dinner
How to Light Shabbat Candles
Tried and True Shabbat Recipes
Shabbat Music