A primer acts as a base for the makeup/foundation that makes the skin appear smoother and even. It acts like glue, holding your skin and your makeup together for hours. It also minimizes the visibility of fine lines, open pores, and dark circles, giving an even, flawless base for the makeup to glide on. Thus, wearing a primer before applying makeup is of utmost importance. 10 Best Primers For Oily Skin and Large Pores