Microbial corrosion is a type of corrosion caused by living organisms such as bacteria, algae, or fungi. This type of corrosion is often associated with tubercles or slimy organic materials.

Corrosion of metals is the process in which metals reach their original oxidation numbers. In fact, corrosion of metals is an oxidation-reduction reaction in which the metal is oxidized by its surroundings. Typically, oxygen from the air acts as the oxidant in these processes.