Final answer:
A cutting comb is a board of fine, upright nails through which human hair extensions are combed, used for detangling or blending colors and highlights.
Step-by-step explanation:
A board of fine, upright nails through which human hair extensions are combed and used for detangling or blending colors and highlights is called a cutting comb. Cutting combs have narrow teeth that are close together, making them ideal for separating and combing through hair extensions.
This tool is commonly used by hairstylists in salons to achieve smooth and even hair extensions, as well as to blend different hair colors and highlights seamlessly. For example, a hairstylist might use a cutting comb to section the hair and then comb the extensions through to create a natural and blended look.