For questions related to the alloy steel: Its production, material properties and applications. The carbon content of steel is between 0.002% and 2.1% by weight for plain iron-carbon alloys.

As steel are referred metallic alloys, whose main constituents are iron and carbon.

This general, common since the early 20th century definition includes the term steel also at that time hardly produced wrought iron, which also had a carbon content of less than 2.06%. The term wrought iron does not describe the components of the alloy, but the method developed over many centuries for producing ductile iron parts, which were essentially based on different types of refining of iron blooms and subsequent forging. Although wrought iron has similar carbon contents as today's steel, but they are not identical due to a slightly different alloy with other substances and not completely removed slag parts.