Chances are, you purchase an incandescent bulb. In fact, Americans buy over a billion incandescent light bulbs every year. These bulbs are inexpensive and can be found in most any grocery, discount or hardware store. They last for about 750 hours, and they don't use much electricity. Well, it depends on how you look at it.
Incandescent bulbs use electricity to heat up a metal filament inside the bulb.
The filament glows and produces light. The remaining energy is given off as heat. Whereas incandescent bulbs use electricity to produce the energy needed to heat the filament, fluorescent bulbs turn more energy directly into light. Fluorescent light tubes contain filament electrodes at each end which allow electricity to flow inside the tube. The inside of the tube is painted with phosphor and it is filled with mercury vapors.