heat sink A Heat Sink is usually a piece of metal that fits tightly to a component that gets hot and would be in danger of destroying itself if it didn't have help in getting rid of all the heat it generates. The heat sink conducts the heat away from the component or device and helps dissipate it to the air, usually by way of having grooves in it to increase it's surface area and therefore conduct heat more efficiently. They are usually held on by a spring clip, or other mechanism for holding it tight against the component. Sometimes they are painted black or have a fan attached to further increase heat dissipation. Take care with small electronic devices, as they often have an insulating sheet/washer and/or a plastic stepped cup washer for electrical insulation from the heat sink.