Ironing is the use of an iron, usually heated, to remove wrinkles and unwanted creases from fabric. The heating is commonly done to a temperature of 180–220 °C (360–430 °F), depending on the fabric. Ironing works by loosening the bonds between the long-chain polymer molecules in the fibres of the material. While the molecules are hot, the fibres are straightened by the weight of the iron, and they hold their new shape as they cool. Some fabrics, such as cotton, require the addition of water to loosen the intermolecular bonds. Many modern fabrics are advertised as needing little or no ironing. Permanent press clothing was developed to reduce the ironing necessary by combining wrinkle-resistant polyester with cotton.

A clothes iron is a small appliance that, when heated, is used to press clothes to remove wrinkles and unwanted creases. Domestic irons generally range in operating temperature from between 121 °C (250 °F) to 182 °C (360 °F). It is named for the metal (iron) of which the device was historically made, and the use of it is generally called ironing, the final step in the process of laundering clothes.