A rotor is a rotating part of a machine that is essential for its operation. In helicopters, for example, the rotor blades spin to create lift, allowing the aircraft to rise and maneuver in the air. Similarly, in electric motors, rotors work with stators to convert electrical energy into mechanical energy. Rotors can also be found in various devices, such as wind turbines, where they capture wind energy to generate electricity. In automobiles, rotors are part of the braking system, helping to slow down or stop the vehicle by creating friction with brake pads.