Essentially, Cathodic Protection (CP) is the intentional application of a direct electric current in opposition to the naturally occurring electrochemical corrosion of metal. Cathodic Protection is now a generally accepted and economical practice for reducing or eliminating the corrosion of metals, particularly steel. Steel structures as varied as underground storage tanks, ships' hulls, oil well casings, hot water heaters, gas pipelines, concrete reinforcing, steel bridges, and offshore drilling rigs are successfully protected by cathodic protection.