How do fridges work and what are the key mechanisms involved in their operation?

Refrigerators work by using a refrigerant to absorb heat from inside the fridge and release it outside. The key mechanisms involved are the compressor, condenser, evaporator, and expansion valve. The compressor pressurizes the refrigerant, the condenser releases heat, the evaporator absorbs heat, and the expansion valve controls the flow of the refrigerant.