A serum is a potent cocktail of plant extracts, antioxidants and vitamins often made in a base of oil that you can apply to your skin after cleansing but before moisturizing. The intention of a serum is to deliver powerful ingredients directly into the skin. Serums are made up of smaller molecules that can penetrate deeply into the skin and deliver a very high concentration of active ingredients. Use them for targeting skin concerns such as wrinkles, acne, pigmentation and more. We love using them day and night under our moisturizer and sunscreen.