The objective of this paper is to study the basic concepts of PID controller and applications in industry. The paper also concentrates on how this concept of PID controller can be used speed control of A. C. motor. With the presented work the author has tried to design and fabricate the experimental set up for studying the speed control of A. C. motor. With the said experimental set up the output characteristics of P, I, D and PID combined controller are obtained. Based on this output characteristics of various combination of controllers and different values, the effect on output is studied. Each type of controller (i.e. P, I, D and PID) has its own effect on the output characteristics. The proportional controller has the effect of reducing rise time but no change in steady state error. The integral controller eliminates the steady state error whereas the derivative controller increases the stability of system. The aim of said work is to study and verify all above characteristics.