Hanukkah always starts at sundown on 25 Kislev on the Jewish calendar. On the calendar most of us use, Hanukkah's dates change from year to year. In 2010, for instance, 25 Kislev=December 1. In 2011, it will be December 20.
Hanukkah (Hanukah / Hanuka / Chanukah) is a festival of lights that is symbolized by the candelabrum known as a menorah. I recently read that menorah refers to a candelabrum with one too few candles and is not the right term; that chanukiah is to be preferred, but I don't know. Do you? If so, please comment.
Hanukkah celebrates a lighting miracle when one night's worth of oil lit candles for 8 days. Special foods and gift-giving are also a part of Hanukkah.
See Winter Holidays, including Hanukkah
Barry Strauss writes about the importance of Hanukkah for the West.

Comments
My friend is a rabbi, and he seems to prefer hanukiah as it’s more specific, but I believe both are correct. Menorah is what I’ve always known Jews in America, the majority of whom are Ashkenazi (roots in Central/Eastern Europe), to call the Hanukkah candle holder. According to this article, hanukiah is a relatively new word that has its roots in the Israeli revival of Hebrew:
http://www.milechai.com/judaism/what-is-a-menorah-and-chaukiah.html
Thanks for the explanation. That make sense.
In Exodus it specifies that the candlestick in the santuary is made with one piece of gold with 3 bowls on one side and 3 on the other and one in the middle. The candlestick used in worship in the temple is the Hebrew word Menorah. The candlestick that is used at Hanukkah has four bowls on each side with a servant candle in the middle representing the 8 days the oil stayed lit.
Hanukkah 2010 officially starts tonight at sundown. Hanukkah Lights for 2010 presents an all-new collection of specially commissioned stories.
Happy Hanukkah, Chanukka : First Day Of Hanukkah Starts Tonight 2010