There are many different types of light bulbs, but none have achieved the energy efficiency of the Light Emitting Diode or LED. Indeed, it has been a revolution in lighting.
Incandescent bulbs are only 20% efficient.
Unlike traditional light bulbs, LED bulbs emit little heat. As much as 90% of their energy goes into producing light. That means replacing your incandescent lights with LEDs can take a chunk out of your monthly energy bill.