Incandescent lamp

The incandescent light bulb is the traditional electric lighting mode. It produces light by heating a filament wire to a high temperature until it glows. The hot filament is protected from oxidation in the air with a glass enclosure that is filled with inert gas.


Compact fluorescent lamp (CFL)

A CFL is a gas-discharge lamp that uses electricity to excite mercury vapor. The excited mercury atoms produce short-wave ultraviolet light producing visible light. A fluorescent lamp converts electrical power into useful light more efficiently than an incandescent lamp. CFLs have two main components: a gas-filled tube (also called bulb or burner) and magnetic or electronic ballast.


Light-emitting diode (LED)

An LED is a semiconductor light source. When the LED is switched on, electrons are able to recombine with electron holes within the device, releasing energy in the form of photons as visible light. LEDs present many advantages over incandescent light sources and CFLs including lower energy consumption, longer lifetime, improved robustness, smaller size, and faster switching.