Question:What is a heat sink?
A "Heat Sink" is anything that is cooler than its surroundings.
A heat sink absorbs heat from the surroundings.
Heat flows towards the heat sink simply because heat always flows from hot to cold.
A heat sink is often associated with something unwanted that takes heat from where we needed it, such as the outside of a house being a heat sink and causing heat losses.
But a fridge is also called a heat sink, because it removes heat from food and drinks and obviously this is desirable.
Heatsinks are used to keep computer chips cool, they consist of piece of copper to conduct the heat away quickly and a fan to blow cool air over the copper to keep it cool to maximize conduction away from the chip.