Hanukkah is an interesting Jewish festival.

It's sometimes referred to as "the feast of lights", or "the feast of (re-)dedication".

Hanukkah 2017 will begin in the evening of Tuesday, 12 December and ends in the evening of Wednesday, 20 December.

It's not part of the Jewish feasts that were given by Moses, but it is referenced in the Bible as "the feast of dedication".

And it was at Jerusalem the feast of the dedication, and it was winter. And Jesus walked in the temple in Solomon's porch.
- John 10:22-23 (KJV)

The story in short:

The books [Maccabees I and II] tell the story, according Chabad, a Jewish-Hasid movement, of how a small band of Jews led by Judah the Maccabee defeated a much larger force and reclaimed the Temple in Jerusalem. When they went to light the temple's menorah - a traditional seven-branched candelabrum - they found only a day's supply of uncontaminated ritual olive oil. The one-day supply of oil lasted for eight days, thus the eight-day celebration.
- Source

I find the use of the phrase "small band" interesting, because it reminds me of Gideon's Band, e.g. 300 warriors that also defeated a much larger army.