While moisturizers have a single purpose — hydration — serums address everything from aging to environmental stress. They’re typically light liquids (for quick absorption) that are packed with active ingredients like antioxidants, retinols, and peptides.
Serums range widely, in both function and price. Take claims with a grain of salt — they’re not going to magic you into Gwenyth — and read the label. A good serum should have tons of actives: hardworking antioxidants like green tea, grapeseed extract, and vitamins A, E, and C, plus anti-aging all-stars like peptides and hyaluronic acid, which tighten and plump skin.
Use it right
Serums only work if they can sink into the skin. Apply them to clean skin before moisturizer or sunscreen. If you have oily skin you can even use a hydrating serum instead of a moisturizer.