A pneumatic actuator is a device that uses pressurized air to convert energy into motion. It is typically used to control a valve, a door, or a machine. Pneumatic actuators are popular in industrial settings due to their low cost, reliability, and ease of use. They are also widely used in consumer products, such as vacuum cleaners and power tools. Pneumatic actuators can be powered by a variety of sources, including compressed air, hydraulic fluid, and electricity. The most common type of pneumatic actuator is the diaphragm actuator, which uses a flexible diaphragm to move a valve stem. This type of actuator is typically used to control the flow of fluids, such as water, oil, and gas. Other types of pneumatic actuators include piston actuators, which use a piston to move a valve stem, and rotary actuators, which use a rotating shaft to move a valve stem. Pneumatic actuators are also used in robotics, where they are used to control the movement of robotic arms and legs.