Wikipedia says that wrought iron has a very low carbon content, making it "tough, malleable, ductile and easily welded." It was the most common form of malleable iron before industrial technology made it practical to manufacture steel in commercial quantitites. Modern steel is, technically, carbon steel because of its high carbon content. Heat-treating carbon steel makes it stronger, harder and less malleable; but in any form it is not easy to weld. Genuine wrought iron is no longer produced commercially. Items advertised as "wrought iron" are carbon steel that is simply worked by hand ("wrought")--or just manufactured to look like it.