Many women use some tool to style their hair each day—whether a blow dryer, a curling iron, or, the one I use most often, a hair straightener. 

The ancestor of the straightening iron was developed by Marcel Grateau in 1872. His tool, popularly called the “Marcel Wave,” was the first to use a heated iron to both curl and straighten hair. This model was effective in styling hair, but because the iron was heated by fire, it could easily burn and damage hair.

Hair straightening went out of vogue in the early 1900s but regained popularity in the middle of the century. Interestingly, women in the1950s and 60s did not adapt the early straightening tool and instead used a clothing iron to flatten their hair. This method was also dangerous and damaged the hair and was later abandoned. For next couple decades, hair straightening was done almost exclusively in salons. 

Today’s commercial straighteners were introduced in the 1990s. New technology allowed lighter metals or ceramic to replace the iron plates of the early models. In addition, many new models allow the user to adjust the temperature of the straightener in order to protect the hair. They also have more functionality, allowing the user to make their hair wavy or curly as well as straight. The lightweight, sleek tools are now a staple in many women’s bathrooms.

Source: http://www.flatironadviser.com/history-of-flat-irons/