Terms of the Trade: What Is a CFL Bulb?

CFL stands for compact fluorescent lamp. Unlike an incandescent bulb, which produces light via a wire filament that glows as current runs through it, CFLs produce light when electric current travels through a tube of argon and mercury vapor. An ultraviolet light excites the fluorescent coating inside the tube, creating visible light. CFLs sell for anywhere from 3 to 10 times more than a regular incandescent bulb, but their lifespan is 8 to 15 times longer and they use up to 75 percent less energy than an incandescent.