A Proportional-Integral-Derivative (PID) controller is the most ubiquitous feedback control algorithm employed in industrial automation and precision instrumentation. It continuously calculates an error value as the difference between a desired setpoint and a measured process variable, applying corrective action through three terms: proportional to the immediate error, proportional to the accumulated historical error (eliminating steady-state offset), and proportional to the instantaneous rate of error change (anticipating overshoot).