What is the benefit of using a top coat on nail polish?

Using a top coat on nail polish primarily serves to add shine and enhance the longevity of the manicure by providing a protective layer over the color polish. This protective layer helps to guard against chipping, scratching, and fading from exposure to elements like water and everyday wear and tear. Additionally, the shine created by a top coat contributes to the overall aesthetic of the nail, giving it a professional and polished look.

In contrast, a matte finish is typically achieved by specific matte top coats designed for that purpose, so it is not a universal benefit of all top coats. While some top coats may slightly affect drying time, traditional top coats are often used to help seal the polish more quickly rather than increase the time it takes to dry. Lastly, top coats do not change the existing color of the polish; they simply enhance its appearance and durability. Thus, the correct answer highlights the key benefits of using a top coat effectively.