The Ner Tamid, or Eternal Light, usually hangs over the Aron Kodesh, or Holy Ark, in every synagogue and is never shut off. It reminds us of the menorah in the Beit HaMikdash, Holy Temple, as well as the altar where the sacrificial incense was burned continually. The Sages say it is a symbol of Hashem's presence in every facet of our lives.