Amperes or amps: The rate at which electricity flows through wires.
Brightness: Light intensity, measured in lumens. The higher the lumens, the brighter the bulb.
CFL: Compact fluorescent light or compact fluorescent lamp, bulbs that use fluorescent technology.
CRI: Color Rendering Index, a scale used to measure color accuracy under artificial light; 100 is considered true color, the same as daylight.
Dimmable: The ability of a light bulb to vary in brightness.
Fluorescent: In a fluorescent light, electricity excites atoms in a mercury vapor, producing ultraviolet light that in turn causes the phosphor powder to “fluoresce” (emit light).
Halogen: Iodine or bromine gas (halogens) used with a tungsten filament to produce a very bright light at very high temperatures in an incandescent bulb. Halogen bulbs use less energy to emit the same light as a standard incandescent bulb.
Incandescent: Emitting visible light as a result of being heated; that’s what happens to the filament inside an incandescent bulb – and why the bulb gets hot to the touch.
LED: Light-emitting diode, a tiny (often a quarter-inch) semiconductor device that emits light when an electrical current passes through it. It stays cool to the touch.
Lumen: Symbolized as “lm,” it’s the measurement used for visible light as perceived by the human eye.
Phosphor: The powder (usually white) used inside fluorescent tubes, CFLs and several new LED bulbs. This powder is often made from rare earth compounds.
Volt: A unit that measure electromotive force; as with water pressure in pipes, higher voltage delivers more energy faster.
Watt: A unit that measures the energy a device uses. Named for Scottish inventor James Watt, who helped develop the steam engine more than 200 years ago. (He also developed the concept of “horsepower,” the measure of how much work can be done.)