How a galvanic cell causes Corrosion?

How a galvanic cell causes corrosion?

A Galvanic cell, or an Electrochemical Cell, is formed when two dissimilar metals are in contact or on the same metal surface when local conditions create different electrochemical potential.

In electrochemical reactions, the electrons are produced by a chemical reaction, the oxidation, in one area, the anode, travel through a metallic path and are consumed through a different chemical reaction in another area, the cathode.

Fundamental of Corrosion Chemistry