Steel is most often made by machines in huge buildings called "steel mills". It is a very cheap metal and is used to make many things. Steel is used in making buildings and bridges, and all kinds of machines. Almost all ships and cars are today made from steel. When a steel object is old, or it is broken beyond repair, it is called "scrap". It can be melted down and re-shaped into a new object. Steel is "recyclable" material; that is, the same steel can be used and re-used.