A refrigerator is a popular household appliance that consists of a thermally insulated compartment and a heat pump that transfers heat from the inside of the fridge to its external environment so that the inside of the fridge is cooled to a temperature below the ambient temperature of the room. Refrigeration is an essential food storage technique in developed countries. The lower temperature lowers the reproduction rate of bacteria, so the refrigerator reduces the rate of spoilage. A refrigerator maintains a temperature a few degrees above the freezing point of water.The refrigerator absorbs the heat inside the fridge, cooling down the air.The refrigerant evaporates to a gas, then flows back to the compressor, where the cycle starts all over.