The primary function of an air compressor is to compress atmospheric air, increasing its pressure and decreasing its volume. This is achieved through a series of components, including a motor or engine to provide power, a compressor pump to compress the air, an air tank to store the pressurized air, and various valves, hoses, and fittings to regulate and distribute the compressed air as needed. Compressor pumps can be classified into different types such as reciprocating, rotary screw, and centrifugal, each offering unique advantages depending on the intended application.