Fluorescent	Halogen	Incandescent	Sodium
The most common types of household lighting are incandescent and fluorescent. The incandescent light, dating back to Thomas Edison, is the least expensive and most common, but it also has a short lifespan and is expensive to operate. Tungsten halogen lights are more energy efficient than ordinary incandescents but are also costly to use and present safety issues. Fluorescent lights are three to four times more efficient than incandescent bulbs, but their harsher glow has traditionally relegated them to commercial or office settings. The compact fluorescent bulb (CFL) has revolutionized people's perceptions of fluorescent light by moving away from awkward tube fixtures and glare-prone light. If every household switched from incandescents to CFLs, it would cut power demand for lighting in half. A 15-watt CFL bulb yields as much light as a 75-watt incandescent. CFL bulbs certified by the federal Energy Star program (and guaranteed for a year) are made by GE, Panasonic, Osram, Sylvania, Philips, MaxLite, and SunPark. CFL bulbs contain small amounts of mercury, so it's important they be recycled properly.