Face primers are cosmetic products applied before foundation to create a smooth base for makeup. They help to fill in fine lines and pores, making the skin appear more even and polished. Primers can also enhance the longevity of makeup, ensuring it stays in place throughout the day. There are various types of face primers, including those that are mattifying, hydrating, or illuminating. Each type caters to different skin types and desired finishes. For example, a mattifying primer is ideal for oily skin, while a hydrating primer works well for dry skin, providing moisture and a radiant look.