A form of lighting which creates light by exposing a conductive vapor to electrical current. The common fluorescent tube used in commercial and household lighting fixtures uses mercury vapor as the conductor. The electrified mercury vapor doesn't actually produce visible light. Instead, it produces ultraviolet light which is converted to visible light by a thin coating applied to the inside of the tube. "Black light" tubes (special-effects lamps which appear to make white objects glow) are created by using a different coating on the inside of the tube that allows more ultraviolet light to pass through.

These lamps are far more energy efficient than standard incandescent lighting since they convert far less electrical energy into heat, but this efficiency is offset by higher cost, especially for smaller household lamps.

Fluorescent lighting can benefit from the use of a device called a ballast which insures steady current flow through the tube. Ballasts contribute to longer tube life by reducing stresses on the tube from rapid changes in power flow. Fluorescent lighting also requires careful monitoring and regular replacement, since some types of tubes emit low levels of x-ray radiation after a period of use at the end points of the tube where the inner coating first begins to wear thin.

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