A pump is a machine that transfers mechanical energy to a fluid. The term “pump” is reserved for machines that handle incompressible fluids. The machines that handle compressible fluids are called compressors. In a pumping operation, the pressure of the fluid will increase and cause it to flow downstream in a direction of lower pressure. On the intake side, we can also think of a pump as a classic suction system, where the pressure is reduced to a level at which fluid flows toward the pump.