Light bulb shopping used to be relatively easy. Traditionally, we would replace our light bulbs based upon wattage. As governments began phasing out the use of incandescent bulbs, replacing them (with CFL, halogen or LED bulbs) has become trickier for consumers. Rather than relying on wattage — the amount of energy needed to power a light bulb — manufacturers are now labeling their products based on other outputs. The most important specs for understanding the effectiveness of light bulbs are lumens, lux, and color temperature.