Have you ever wondered if using a primer makes a difference when it comes to applying your makeup? The last thing any busy woman wants to do is add another step to her beauty regimen, but the short answer is yes, you need a primer -- and here's why. A primer functions in a few ways. First, it seals in moisture from sunscreen or day creams, which should be applied before the primer. There are even a few brands that include SPF, like MAC's Prep & Prime Face Protect SPF 50. Primers go to work, filling in fine lines, large pores and evening out skin tone, creating a smooth, uniform surface for makeup to be applied evenly and cleanly. They come in different hues to correct and enhance different skin tones. Green colors can make acne redness and rosacea less noticeable, while pink helps enhance any complexion. Try a mauve or light purple to counteract sallow skin.