A water block is a liquid cooling component that is placed directly onto the cooled computer component. Its basic function is to transfer heat from this component, such as a processor or graphics card, into the coolant. The base of the block, most often made of copper for good thermal conductivity, is in direct contact with the cooled part. Inside the block, there is a system of channels or fine fins through which the coolant flows. This liquid absorbs heat from the block's base and, once heated, carries it away to another part of the cooling loop, typically to a radiator, where it is cooled again. Water blocks are designed specifically for various types of components; there are blocks for processors, graphics cards, but also for motherboard power delivery sections or RAM. It is a component intended for building a custom cooling loop, unlike closed "All-in-One" coolers where the block is already factory-connected to the pump and radiator.