A twisty compact fluorescent light bulb

Compact fluorescent light bulbs (also called "compact fluorescent lamps" and "low-energy light-bulbs") use far less energy than traditional incandescent bulbs, and surprisingly give off more light, mostly due to their unique "spiral" design. This twisty style of light bulb has a slightly lower efficiency than the tubular fluorescent light bulbs, mostly due to the extremely thick layer of phosphor on the lower side of the twist part of the bulb, which allows the light to be distributed outwards.

In fact, CFLs can not only save you money in energy, but they are often rated higher in hours of life expectancy, which are often a concern with traditional bulbs. Studies have shown that a single compact fluorescent light bulb can save over thirty dollars in electricity costs over the lamp's lifetime compared to an incandescent bulb and save nearly 2,000 (two thousand) times its own weight in greenhouse gases--and that's no joke!