Shopped for light bulbs lately? If you have, you may have noticed that most bulbs sold now are LED (light emitting diode) bulbs. Old-fashioned incandescents have all but vanished from store shelves, and the popularity of CFL (compact fluorescent light) bulbs is on the wane. That's because, although they're more energy efficient than incandescents, CFLs just can't compete with the energy efficiency and light quality of LED bulbs. And, while you're lucky to get two to five years of life from a CFL bulb, LED bulbs can last 20 years or more. But trying to figure out which LED bulbs to buy can lead to a lot of head scratching. Here's what you need to know before you shop.