Fluid energy is the use of fluids under pressure to generate, control and transmit power. The energy of the fluid is subdivided into hydraulics using a liquid such as mineral oil or water, and pneumatics using a gas such as air or other gases. Compressed air and water pressure systems were once used to transmit power from a central source to industrial users in extended geographical areas; Fluid power systems today are typically within a single building or mobile machine. A fluid energy system has a pump driven by a primary motor (such as an electric motor or an internal combustion engine) that converts mechanical energy into fluid energy. Directed by valves to an actuator device such as a hydraulic cylinder or pneumatic cylinder, to provide linear motion, or a hydraulic motor or pneumatic motor, to provide rotary or torque motion. The rotary motion may be continuous or limited to less than one revolution.