The most common way of the primary ways of producing light. Incandescence is the ability of an object to give off light when heated. In an incandescent lamp, large amounts of electricity are passed through a small filament, usually made of tungsten. Due to resistance in the filament, it quickly heats up and then glows. Further explanation at this site.
Also see Gaseous Discharge and Fluorescence.
Also see Gaseous Discharge and Fluorescence.