n incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated to a high temperature, by passing an electric current through it, until it glows with visible light (incandescence). The hot filament is protected from oxidation with a glass or quartz bulb that is filled with inert gas or evacuated. In a halogen lamp, filament evaporation is prevented by a chemical process that redeposits metal vapor onto the filament, extending its life. The light bulb is supplied with electric current by feed-through terminals or wires embedded in the glass. Most bulbs are used in a socket which provides mechanical support and electrical connections.