Iron is a common metal. When iron ore is heated in a furnace, liquid iron metal can be produced. However, iron formed from a furnace is not the most useful form of the metal because it contains too much carbon and so is brittle. Most of the iron is changed into steel by removing most of the carbon.

Carbon is removed from molten iron by blasting oxygen across its surface. The carbon joins with the oxygen to make carbon dioxide gas. The amount of carbon taken out of the metal can be controlled by blasting the oxygen through the metal for a certain time. This allows different kinds of steel to be made.

Steels with the most carbon in them are called hard steels. They are still quite brittle. Steels with the least carbon in them are called soft steels. They are most easily shaped.

Hard steel is used to make scissors and knives, medium steel used to make springs and rails, mild steel is used to make girders and plates for ship's hulls, and soft steel is used for making cans, car bodies, and wire.

Changing iron to steel does not give it better resistance to rusting. To achieve this steel has to be combined with other metals, for example chromium. This makes stainless steel.