What is an LED, and what makes them better than incandescent bulbs? When electrical current is applied, an LED (light emitting diode) will project light from a semiconductor chip mounted on a circuit board. This provides a much more efficient means of light generation with little heat, over that of incandescent, halogen and xenon bulbs. LEDs typically generate 70+ lumens per watt, which shadows the output of incandescents at 15, and xenons at 20-25 lumens per watt.