Chanukah is the 8-day Festival of Lights in December. It commemorates the rededication of the Temple in Jerusalem after the Maccabees had defeated the Syrians in 165 BCE.
During the rededication, a single jar of oil was used to relight the seven stemmed candelabrum (Menorah) in the temple. There was oil in the jar for only one day, but miraculously, the candelabrum burnt for eight days. After the destruction of the Temple in 70 CE, Chanukah continued to be celebrated as the Festival of Lights. It celebrates the reaffirmation of Jewish identity. To remember the miracle, the Chanukia (eight stemmed candelabrum) is lighted at home and in the synagogue for eight days; each evening an additional candle is lit using an extra ninth candle.