Serums are lightweight skincare products that contain a high concentration of active ingredients. They are designed to penetrate deeply into the skin, delivering targeted benefits such as hydration, brightening, or anti-aging effects. Unlike creams or lotions, serums typically have a thinner consistency, making them ideal for layering under other products. Common ingredients found in serums include hyaluronic acid for moisture, vitamin C for brightening, and retinol for reducing fine lines. Serums can be used daily, often applied after cleansing and before moisturizing, to enhance the overall effectiveness of a skincare routine.