What hair styling technique uses heat to create curls?

Using heat to create curls is most commonly associated with the technique of curling with either a flat iron or a curling iron. These tools are designed to effectively apply direct heat to the hair, causing the hair strands to reshape and form curls. The curling iron is specifically made for this purpose, featuring a barrel that heats up and allows hair to wrap around it, creating defined curls or waves based on the size of the barrel and the technique used.

While pin curling, rolling hair in rollers, and twisting strands can all create curls, they primarily rely on setting and sometimes texture without direct heat. Pin curling involves twisting the hair and holding it in place with pins, setting hair in rollers usually requires moisture or setting lotions, and twisting strands primarily creates waves or curls without heat and is more about manipulating the hair's natural pattern. Thus, the definitive use of heat in curling with a flat or curling iron makes it the most effective and straightforward method for creating curls.