What is called Rusting?

Rust is nothing but iron oxide. Prolonged exposure to air or water causes iron to turn reddish brown. This reddish brown coating is called rust. Essentially, rusting is a chemical reaction between iron and oxygen. To avoid the problem of rusting, alloys of iron came into use. For example, we cook in utensils made of stainless steel than iron. A way to prevent rusting of iron are use of lubricants like oil to cut the air supply. Use of paint also prevents air from coming in touch with surface of the metal.