Fluid mechanics is the branch of physics that studies the behaviour of fluids when they are in motion or at rest. Hydraulic machinery is a branch of engineering that focuses on the design, construction, and operation of machines that use fluids to transmit power. It includes flow measuring devices, apparatus to study open channel flow behaviour, and machines such as pumps, turbines, and hydraulic motors, which use the properties of fluids to generate power or motion. It is important to understand the functioning principles and characteristics of fluid motions as well as the operation of hydraulic machines from an engineering point of view.