How does a refrigerator actually keep food cold inside?

A refrigerator works by continuously circulating a chemical refrigerant through a closed loop system. The refrigerant absorbs heat from inside the fridge as it evaporates into a gas in the evaporator coils, which are located inside the compartment. This heat absorption is what makes the interior cold. The compressor then pressurizes the gas, which causes it to heat up, and it moves to the condenser coils on the back or bottom of the fridge where it releases that heat into your kitchen air and returns to liquid form. The cycle repeats constantly, effectively pumping heat from inside the refrigerator to outside it. The insulated walls simply slow down new heat from entering, making the compressor's job more manageable.