In the 1st Century BC metal pans filled with charcoal were used for smoothing fabrics in China. In the 17th century solid irons used to be heated in fire. Later an iron box filled with hot coals starting to be more and more popular.
In the late 19th century were many irons which were heated by fuel as kerosene, alcohol, whale oil, natural gas or gasoline.
Nowadays we count with electric irons which uses resistive heating from an electric current. The hot plate is made of aluminium and it can be control by a thermostat. This electric iron creation was made by the New Yorker Henry W. Seeley in 1882. The early electric irons had no easy way to control their temperature.