Three-term control: PID control

PID or three-term controllers are widely used in industry. For example, in atypical paper mill there may be about 2000 control loops, and over 90% of these would be PID control loops. The PID name comprises the first letters of the three terms which make up this controller: P stands for the Proportional term in the controller I stands for the Integral term in the controller D stands for the Derivative term in the controller In the mid-1900s, several technological and analysis concepts came together to make the PID controller widely accepted as an effective industrial controller.