It’s easy to want to slather on every lotion, serum, peel, and eye cream you can get your hands at in the name of youthful, glowing, clear skin. Stylecaster spoke with two experts, Annie Chiu, a dermatologist at The Derm Institute, and Joshua Zeichner, Director of Cosmetic and Clinical Research in Dermatology at Sinai Hospital in New York City to find out more about glycolic, ferulic, L-ascorbic, and retinoic acids, among others—plus which is the best skin acid for your complexion concerns. Ahead, a primer and the best products to shop. Lactic Acid An alpha hydroxy acid (which means it’s water-soluable, rather than lipid-soluable), lactic acid works on surface skin, making it great for sensitive skin. Read more at stylecaster.com.