How Light Bulbs Work

Before the invention of the light bulb, illuminating the world after the sun went down was a messy, arduous, hazardous task. It took a bunch of candles or torches to fully light up a good-sized room, and oil lamps, while fairly effective, tended to leave a residue of soot on anything in their general vicinity.

Newer types of light bulbs, like more energy efficient and longer lasting CFLs, are… » Full Story on HowStuffWorks