A well-tuned PID controller's reward is that nobody notices it.

A PID controller is a feedback control system that continuously adjusts an output to keep a measured process close to a desired setpoint. PID stands for proportional, integral, and derivative control. The proportional term responds to the current error, the integral term responds to accumulated past error, and the derivative term responds to how quickly the error is changing. Combining these three actions allows the controller to reduce steady-state error, improve response speed, and limit overshoot or oscillation. Proper tuning determines how strongly each term influences the system. PID controllers are used in industrial automation, robotics, motor control, and process control.