Hydraulics is a topic in applied science and engineering dealing with the mechanical properties of liquids. Fluid mechanics provides the theoretical foundation for hydraulics, which focuses on the engineering uses of fluid properties. In fluid power, hydraulics is used for the generation, control, and transmission of power by the use of pressurized liquids. Hydraulic topics range through most science and engineering disciplines, and cover concepts such as pipe flow, dam design, fluidics and fluid control circuitry, pumps, turbines, hydropower, computational fluid dynamics, flow measurement, river channel behaviour and erosion.
Pneumatics is the use of pressurized gas to affect mechanical motion.
Pneumatic power is used in industry, where factory machines are commonly plumbed for compressed air, other compressed inert gases can also be used. Pneumatics also has applications in dentistry, construction, mining, and other areas.