The festival is observed by the kindling of the lights of a unique candelabrum, the nine-branched Menorah or Hanukiah, one additional light on each night of the holiday, progressing to eight on the final night. The typical Menorah consists of eight branches with an additional raised branch. The extra light is called a Shamash and is given a distinct location, usually above or below the rest. The purpose of the shamash is to have a light available for use, as using the Hanukkah lights themselves is forbidden.
This video clip is of a rabbi who very concisely explain the background of the holiday as well how it is celebrated now. I chuckled a bit when I found this clip because I think of a rabbi as an old, wise-looking man with a white beard. He looks like a bishop from the LDS church.