Oxidation and Reduction

Oxidation is the gain of Oxygen and Reduction is the loss of Oxygen
The extraction of metals from their oxides is reduction.

Most metals corrode. The corroding of metals is called Rusting. Corrosion happens when the surface of the metal is changed by the reaction with Oxygen. When metals corrode the metal is oxidised.

The more reactive the metal, the more rapidly it corrodes. Metals with low reactivity are more resistant to oxidation and corrosion. For example, Gold does not corrode at all.