Galvanic (Sacrificial) Anode

When two different metals are physically or electrically connected and immersed in electrolyte (e.g. seawater as show below), there will be a current flow between the two metals. This current is supplied by the metal of high activity (anode) by emitting metal ions to the electrolyte. This is known as galvanic corrosion which destroys anode rapidly.

The protected metal becomes a cathode with uniform potential across itself, and thus corrosion is prevented, and Cathodic Protection is achieved.