Festival of Lights

"According to tradition, when the Maccabees entered the Holy Temple, they discovered that the Greco-Syrians had defiled the oil which was used to Temple's menorah. Only one vat of purified oil remained - enough for only one day. It would take the Jews a week to process more purified oil. Then a miracle occurred. The Maccabees lit the menorah and it burned for not one, but eight days, by which time the new, purified oil was ready. This is why the Hanukkah Menorah has eight candles (not including the shamash candle used to light the others) and one reason why Jews celebrate Hanukkah for eight days."

Read more here.