What does a curling iron primarily do?

A curling iron is specifically designed to add curls or waves to hair. Its functionality centers around heating a metal barrel, which when wrapped with hair, creates a curled or waved pattern as the heat is applied. This tool is essential for hairstyling techniques aimed at enhancing texture and volume through curls or waves.

While other options may relate to hair tools or processes, they do not accurately describe the primary function of a curling iron. For instance, straightening hair is typically the domain of straightening irons; drying hair quickly would refer to a blow dryer, and sealing hair ends often involves different products or tools, such as serums or styling creams. Thus, the defining characteristic of a curling iron is its ability to transform straight or wavy hair into defined curls or waves.