A cosmetic ingredient is any substance used in the formulation of beauty and personal care products. These ingredients can serve various purposes, such as cleansing, moisturizing, or providing color. Common examples include water, glycerin, and fragrance. Cosmetic ingredients are carefully selected for their effectiveness and safety. They can be derived from natural sources, like plants, or created synthetically in laboratories. Understanding these ingredients helps consumers make informed choices about the products they use on their skin and hair.