This is a type of iron, which unlike hard, brittle pig iron – such as is tapped from a blast furnace – is tough and malleable, allowing it to be forged and welded. It has a high tensile strength and is more corrosion resistant than steel.
Wrought iron has a very low carbon content – lower than many steels – but importantly it has traces of manganese/sulphur/phosphorus/silicon-containing slag which give it a fibrous structure and which contributes to its desirable properties.
Wrought iron was widely used for structural, engineering and decorative applications, and consumption declined after the mid-nineteenth century once steel became more widely available. Small amounts are produced today for artistic applications and restoration work. Arguably the most famous example of wrought iron in action is the Eiffel Tower, Paris. And for more detail click and see wikipedia entry.