What is it exactly?
You wouldn’t just apply paint to a wall without priming it – the color would go on all smudgy and gross. The same goes for your face, which has all sorts of bumps, pores, dry patches, and lines that are natural and normal but terrible for makeup application. Primer glosses over all those uneven areas to give you a smooth base for makeup; it’s also formulated to help makeup adhere to the skin longer.
Finding the right primer
There are hundreds of primers out there and finding the right one can be maddening (and breakout-inducing). Face primers fall into two basic categories: lotions and silicone-based gels. Lotions are typically lighter and often come with bells and whistles like SPF, anti-aging actives, or redness-neutralizing ingredients. Silicone-based primers have a slick feel and give your skin a velvety matte texture. These are great for drier complexions because they give you a glass-like surface; they also tend to be more heavy-duty (ideal for events). Be sure to test any primer for at least a week to see how it interacts with your skin.
Eyes, lips, and more
Your eyes and lips need primer as much as your face (and maybe even more). Eyelids tend to be oilier than other parts of the face, which is why eyeshadows migrate south during the day. Eye-specific primers are fairly dry formulas that keep shadows from sliding or fading. Until recently I thought lip primers were simply a more expensive Chapstick — not true. Lip primers smooth out the natural lines and crevices in your mouth so when you apply color it looks uniform and glossy, not cracked and icky. If you’re not wearing bright lipstick (which you should be), you can skip primer.