Glycolic Acid, Purity : 100%, Form : Liquid

Glycolic acid is a colorless, odorless alpha-hydroxy-acid (AHA) derived from sugarcane. It’s a type of chemical exfoliant that dissolves the bonds between dead skin cells, allowing them to be wiped away easily, revealing smooth, younger skin below.

It’s actually the smallest naturally occurring AHA, Zeljka Kreptic, Ph.D., a lecturer in physical chemistry at the University of Salford, tells SELF. That means it can penetrate the skin more deeply and easily compared to other AHAs you might know, like lactic acid, which is why it is so commonly used.

AHAs like glycolic acid are water soluble, which means they dissolve in water. On the other hand, beta-hydroxy-acids (BHAs), such as salicylic acid, are oil soluble, meaning they dissolve in oil and can penetrate deeper into oily pores, Marisa Garshick M.D., board-certified dermatologist at the Manhattan Dermatology and Cosmetic Surgery Center, tells SELF.

But that doesn’t mean AHAs aren’t effective. If used correctly, as in a glycolic acid peel, they can be an easy way to get smoother, glowing skin.