The festival is observed by the lighting of candles on the nine-branched Menorah. One additional light for each night of the holiday, progressing to eight on the final night. An extra light called a Shamash (Guard) is also lit each night for the purpose of lighting the others, and is given a distinct location, usually above or below the rest. The "shamash" symbolically supplies light that may be used for some secular purpose.
This was a really, really bad idea. As it turns out, there were plenty of jews who didn't take to kindly to un-clean animals being sacrificed to a pagan god in their sacred temple. So Mattathias, a local priest, and his five sons, led a rebellion against Antiochus. His son Judah became known as Yehuda HaMakabi ("Judah the Hammer"). By 166 BCE Mattathias had died, and Judah took his place as leader. By 165 BC the Jewish revolt against the Seleucid monarchy was a success. The Temple was liberated and rededicated. The festival of Hanukkah was instituted by Judah and his brothers to celebrate this event. After recovering Jerusalem and the Temple, Judah ordered the Temple to be cleansed, a new altar to be built in place of the polluted one and new holy vessels to be made. According to the Talmud, olive oil was needed for the menorah in the Temple, which was required to burn throughout the night every night. But there was only enough oil to burn for one day, yet miraculously, it burned for eight days, the time needed to prepare a fresh supply of oil for the menorah. An eight day festival was declared by the Jewish sages to commemorate this miracle.