Iron is a transition metal that is abundant in the earth’s crust. It is a very important element that is used in construction, manufacturing, and medicine. Iron’s most important application is in the production of steel, which is an alloy that is made by mixing iron with small amounts of other elements, such as carbon. Steel is used in a variety of applications, including construction, transportation, and machinery. Iron is also used in medicine as a dietary supplement and in the treatment of anemia.