How do refridgerators work?

Refrigerators and air conditioners are heat pumps. They move heat from one place to a different place. They use a working fluid with a low boiling point to do this, e.g. hydrofluorocarbons like HF3C. This working fluid is compressed by a compressor until it liquifies. However it also becomes hot, so the compressed liquid is passed through radiator coils to dispose of the unwanted heat (typically on the back of a refrigerator or the outside part of an air conditioner). The liquid working fluid, now at about room temperature, passes through a small hole as it enters the cooling coils which are at low pressure. The working fluid evaporates inside the cooling coils, reducing their temperature. The gaseous working fluid is then compressed back to liquid by the compressor and the cycle continues.