Iron (named from iren, the Old English name) is the 26^th element.  The earth's crust is about 5.8% iron by weight.  It is the second most abundant metal and is the most frequently used metal in industrial nations.  The ores from which it is extracted are iron oxides.

The Iron Age was a period of human culture that was characterized by the smelting of iron and its use beginning sometime before 1000 BC in Asia and Egypt.  Wrought iron is somewhat soft and cannot be hardened by tempering.  When iron is alloyed with a small amount of carbon, it becomes harder and tougher and is called steel.  Tool steel is formed when the percentage of carbon reaches 1.5%.

Iron is found in hemoglobin, the compound that carries oxygen in the bloodstream.