What is the function of a primer in makeup application?

The function of a primer in makeup application is primarily to create a smooth base for the makeup and enhance its longevity. Primers are formulated to fill in fine lines, pores, and other imperfections on the skin, allowing foundation and other makeup products to apply more evenly and adhere better. This results in a flawless finish that lasts longer throughout the day.

While other options describe important aspects of skincare and makeup application, they do not encompass the primary purpose of a primer. Correcting color imperfections pertains more to the use of color correctors, hydrating the skin falls under skincare moisturizers, and providing sun protection is associated with sunscreen products. Thus, the defining characteristic of a primer is its role in smoothing out the skin's surface and extending the wear of makeup.