Proportional gain (P) represents the level of aggressiveness in the PID controller. The P parameter is like a gain multiplier. High P value means more aggressive PID controller action, called proportional contribution. Integral tuning parameter (I) represents the level of impatience in the PID controller. Most of the times the ā€œIā€ parameter is in the denominator. Derivative parameter (D) shows the level of anticipation based on past history of PV movement (PV trajectory ). When dead time is long, adding derivative is like being able to increase the proportional gain without causing oscillations. Derivative action is lead response of the PID controller which compensates the process lag. The complete and detail behavior of a fully blown PID algorithm can be nicely seen in Figure 2.