Incandescent Light Bulb Filament
The standard incandescent lamp is made up of a small length of Tungsten alloy wire. It is coiled up to conserve space. The filament is heated by passing a DC current through the wire where it reaches white hot temperatures. The filament is generally protected from oxidation by air by using a glass bulb filled with an inert gas. These are inefficient but cheap devices, converting ~ 5% of the energy they consume into light, the rest is waste heat. You can see the effect of this heat on the filament itself as it is becoming faceted due to an annealing of the metallic structure. Today incandescent lamps they are being replaced by LED's and CFL's.