An iron is a household
appliance used to smooth out
wrinkles and set
creases in
clothing and
drapery. Typically an iron consists of a flat metal surface with holes in it, a
plastic body which contains a well for water, and a handle. The metal surface is heated up to a high temperature (highest for
cotton and other sturdy fabrics, lower for more delicate materials, particularly
synthetics which have an unfortunate tendency to melt in high heat), and water is released through the vents as steam. The combination of heat and water vapor against the flat surfaces works to press the cloth very effectively. Irons are usually used on an
ironing board, a small table with an insulated surface which prevents the heat from damaging it.
Today's irons are heated electrically, but irons certainly predate the era of easily available electricity. Traditional irons were indeed slabs of iron (with a handle of wood or some other material that wouldn't burn your hand), heated on a hot stove.
The word iron can also more generally denote a tool used in a similar way to heat and shape things - for instance, a soldering iron is a metal tool with a handle that is heated to a high temperature to melt solder to join objects - or to describe a tool made of (or traditionally made of) iron.