(Wikipedia excerpt:..”An electric light is a device that produces visible light from electric power. It is the most common form of artificial lighting and is essential to modern society, providing interior lighting for buildings and exterior light for evening and nighttime activities. In technical usage, a replaceable component that produces light from electricity is called a (L). (L) are commonly called light bulbs; for example, the incandescent light bulb. (L) usually have a base made of ceramic, metal, glass, or plastic, which secures the lamp in the socket of a light fixture.
The electrical connection to the socket may be made with a screw-thread base, two metal pins, two metal caps or a bayonet cap. The three main categories of electric lights are incandescent lamps, which produce light by a filament heated white-hot by electric current, gas-discharge (L), which produce light by means of an electric arc through a gas, such as fluorescent (L) , and LED (L), which produce light by a flow of electrons across a band gap in a semiconductor….” ).