As the light-emitting diodes create light, they warm up quite a bit for their size. LEDs are heat sensitive, so it's important that the heat move away so that it doesn't damage the semiconductors. In order to do this, these lights need a system to keep cool. Most LED lights have a heat sink plate that moves the heat away from the light-emitting diodes through the heat sink plate. Manufacturers make the heat sink plate out of a variety of materials, but it's commonly made from aluminum. Frequently, the heat sink becomes part of the design of the bulb.