Cathodic protection or CP, in short, is a method that is used for controlling corrosion of any metal surface. It does so by making those metal surfaces as the cathodes of electrochemical cells. In the process of cathodic protection, the metal that needs to be protected is connected to a sacrificial metal to act as an anode. The metal that acts as an anode in this connection is relatively easily corrodible. Hence it is also called the sacrificial metal and has relatively lesser importance. The sacrificial metal in this process corrodes in place of the metal that we intend to protect. For constructions such as the long and big pipelines, in which inert galvanic cathodic defense is not sufficient, as external DC (Direct Current) power source is applied in order to suffice the provision of electric current.