A galvanic anode is one of the main components of a galvanic cathodic protection system used to protect a metal structure from corrosion.

The first use of CP was in 1824, when Sir Humphry Davy, of the British Navy, attached chunks of iron to the external, below water line, hull of a copper clad ship. Iron has a stronger tendency to corrode then copper and when connected to the hull, the corrosion rate of the copper was dramatically reduced.

Today, galvanic anodes are made in various shapes using alloys of zinc, magnesium and aluminum. The electrochemical potential, current capacity, and consumption rate of these alloys are superior for CP than iron.

Galvanic anodes are designed and selected to have a more "active" voltage (technically a more negative electrochemical potential) than the metal of the structure (typically steel). For effective CP, the potential of the steel surface is polarized (pushed) more negative until the surface has a uniform potential. At that stage, the driving force for the corrosion reaction is halted. The galvanic anode continues to corrode, consuming the anode material until eventually it must be replaced. The polarization is caused by the current flow from the anode to the cathode. The driving force for the CP current flow is the difference in electrochemical potential between the anode and the cathode.