The curling iron was invented in 1872 by Frenchman Marcel Grateau, who used metal tongs that were heated over a gas burner. The style he created with the tongs was called the Marcel wave.
Grateau's curling tongs operated like a pair of scissors. The user opened the handle, inserted the hair and closed the tongs to create a crimp. A long piece of hair could be wrapped around the tongs to create a curl. This system required the user to keep the handle closed while the hair was curling. Modern-day curling irons employ a spring-loaded handle that holds the hair against the iron.