What characteristic is unique to a top coat compared to a regular nail polish?

A top coat is specifically designed to enhance the longevity and durability of a manicure by forming a protective layer over the colored nail polish. One of its primary functions is to prevent chipping and breaking, which is crucial for maintaining the integrity of the nail polish underneath. This protective quality distinguishes top coats from regular nail polishes, which do not have the same level of protective ingredients or formulation focused on prolonging wear.

While some top coats are also formulated to provide a glossy finish and may harden more quickly than some nail polishes, these features can vary widely between products and are not universally unique to top coats. Colored top coats do exist, but the primary defining characteristic that sets them apart is their ability to prevent chips and breaks, rather than just these aesthetic or application-related qualities.