What is a trimmer primarily used for in barbering?

A trimmer, also known as a detailer, is primarily utilized for detailing and edging the hairline. This tool is designed to create fine lines around the edges of hairstyles, including around the temples, the nape, and the beard area. Its precision allows barbers to achieve a sharp, clean look that enhances the overall style and finish of a haircut.

In contrast, the other options refer to different aspects of hairstyling: creating layers involves using scissors or clippers with specific techniques to remove bulk and add texture, which is not the purpose of a trimmer; styling wet hair typically requires tools like combs or blow dryers; and cutting long hair evenly relies on shears or clippers, as trimmers lack the necessary length-adjustment capabilities required for such tasks. Thus, the primary function of the trimmer is to provide the fine detailing that completes a haircut.