There are three types of corrosion general attack corrosion, localised corrosion, galvanic corrosion and environmental cracking. 

The chemical reaction in which iron (Fe) combines with oxygen (O2) to form rust, or iron oxide (Fe2O3). The equation for this reaction is: 4 Fe+ 3O2 → 2Fe2O.

All metals containing iron, such as most kinds of steel will rust when exposed to air and water. Rust is just iron oxide, usually with water molecules incorporated in it too. It usually takes the form of an orange powder on the surface of the metal.

Rusting is a chemical reaction between iron and oxygen. it is an exothermic reaction because heat is released during the reaction. This reaction is simply an exothermic reaction where the energy released is in the form of light. Photosynthesis is an endothermic reaction where light (energy) is required.

All metals can corrode. Some, like pure iron, corrode quickly. Stainless steel, however, which combines iron and other alloys is slower to corrode and is therefore used more frequently.

The Reactants. The first required reactant in combustion is a fuel. Many of these fuels, called combustibles, are organic. Organic materials contain carbon, hydrogen and oxygen. Hydrocarbon + oxygen → carbon dioxide + water is the chemical equation for combustion.

The negative effects of combustion on the environment particularly greenhouse gas emissions released to the atmosphere that contribute to global warming have received much attention in recent years. 

Combustion occurs in everyday life with burning coal and wool, so you smell smoke, you feel heat and you see fire or smoke and you hear bubbling or crackles from the fire.