Consider two metals joined together, one that reacts more readily with its environment than the other. The more reactive one keeps giving up its electrons and corroding away first, while the electrons it releases flow over to protect the less reactive metal, keeping it safe. Since this reactive metal is deliberately sacrificed to save the main structure, engineers call this approach cathodic protection using a sacrificial anode, commonly done with zinc or magnesium blocks on ship hulls and pipelines. Anodic protection instead applies an outside current to push the metal into a passive state, and passivation happens on its own through a natural oxide film, neither one involves connecting a second reactive metal. So the technique described is cathodic protection.