A PID (Proportional–Integral–Derivative) Controller is a feedback control mechanism used to minimize the error between a desired setpoint and the actual output of a control system. It combines three actions: the proportional (P) term responds to the present error, the integral (I) term accumulates past errors to reduce or eliminate steady-state error, and the derivative (D) term predicts future error based on its rate of change, helping reduce overshoot and improve system stability. The PID control law is commonly expressed as $u(t)=K_p e(t)+K_i\int e(t)\,dt+K_d\frac{de(t)}{dt}$, where $K_p$, $K_i$, and $K_d$ are the proportional, integral, and derivative gains, respectively. PID controllers are widely used in motor speed control, temperature regulation, robotics, process control, and many other engineering applications.