In this chapter, pumps, which belong to the power-consuming class within the incompressible flow category, are discussed in detail. The chapter starts with a chart that is used in the selection of pumps. It is seen that for extremely high heads, positive displacement pumps are used, and as the flow rate increases, the design of pumps changes from centrifugal to axial flow. By making simple assumptions, a relationship between the head developed and flow rate is derived. Using this relationship, it is shown that backward-curved blades are most suitable for centrifugal pumps to avoid surging. Piping systems and pumping characteristics are discussed next. Based on the best efficiency, the method of selecting the correct operating point and rotational speed is discussed. Variations of viscosity, speed, diameter, and the number of pumps on the system curve are demonstrated. The chapter concludes with a detailed discussion of cavitation using the concept of net positive suction head and how to change the pump settings to avoid cavitation. Basic design features of pumps are also discussed.