An actuator is a device that produces force, torque, or displacement, usually in a controlled way, when an electrical, pneumatic, or hydraulic input is supplied to it in a system. It converts such an input signal into the required form of mechanical energy, making it a type of transducer. Actuators are present in almost every machine around us, from simple electronic access control systems, household appliances, and vehicles to industrial devices and robots. There are two main types of actuators: linear and rotary. Linear actuators produce linear motion, meaning they can move forward or backward on a set linear plane, while rotary actuators produce rotary motion, meaning they revolve on a circular plane. Actuators can be powered by electricity, air, or hydraulic fluid pressure, depending on the application and industry-specific requirements. Some common examples of actuators include electric motors, stepper motors, jackscrews, and electric muscular stimulators in robots. Actuators are used in various applications, such as automated control of fluid flow in pipelines and process systems, adjustment of solar panels, and positioning of medical equipment.