Cathodic Protection is a method used to control the amount of corrosion that occurs on a metal surface by converting the anodic sites on metallic surfaces into cathodic by introducing electrical current from an alternate source.  One of the most common sources used are galvanic anodes, which are more active than steel. This practice is also referred to as a sacrificial system, since the galvanic anodes sacrifice themselves to protect the structural steel or pipeline from corrosion.