From The Jerusalem Connection:

Hanukkah is the eight day Jewish holiday known as the “festival of lights” or “feast of dedication.” Each year the holiday falls sometime between late November and the end of December. In 2012, Hanukkah will last from December 8th to the 16th.  Hanukkah is the celebration of a miracle that happened over 2,100 years ago. In 175 BCE, the Syrian-Greek king Antiochus IV (his nickname was “madman”) led his army into Jerusalem where he took over the city and the Temple.

The most important tradition each night of Hanukkah is the lighting of the menorah to celebrate the miracle of the oil. The Hanukkah menorah (called the hannukkiyah) has eight candles plus a candle used as the lighter called the “shamash.” On the first night of Hanukkah one candle is lit, and on the next night two are lit, and so on. On each night, the leftmost candle is lit first, and lighting proceeds from left to right. By the last night, all eight candles burn.