What technique involves drying and styling damp or wet hair in one step?

Blow dry styling is the technique that allows for both drying and styling damp or wet hair in a single step. This process utilizes a blow dryer equipped with various attachments, such as a concentrator nozzle or diffuser, to direct airflow and heat onto the hair.

The heat not only evaporates the moisture from the hair but also helps shape and set the style as it dries. By using brushes or other styling tools during this process, a variety of styles can be achieved, from smooth and straight to voluminous curls. The efficiency of blow dry styling makes it a popular choice for many barbers and stylists looking to save time while achieving polished results.

Other techniques listed do not fulfill both roles simultaneously; for example, flat ironing mainly focuses on straightening already dried hair, roller setting is usually performed on damp hair but requires additional drying time afterward, and diffusing is specifically a technique used to dry curly hair while maintaining texture and volume but does not inherently style in a traditional sense.