Cosmetics are substances that are intended for application to the body for cleansing, beautifying, promoting attractiveness, or altering appearance. They are mixtures of chemical compounds derived from either natural sources or created synthetically. Cosmetics have various purposes, including personal and skin care. They can also be used to conceal blemishes and enhance natural features (such as the eyebrows and eyelashes). Makeup can add color to the face, enhance features, or alter appearance to resemble a different person, creature, or object.

People have used cosmetics for thousands of years for skin care and appearance enhancement. Visible cosmetics for both women and men have gone in and out of fashion over the centuries.

Some early cosmetics contained harmful ingredients, such as lead, which caused serious health problems and sometimes resulted in death. Modern commercial cosmetics are generally tested for safety but may contain controversial ingredients, such as per- and polyfluoroalkyl substances (PFAS), formaldehyde releasers, and ingredients that cause allergic reactions.

The European Union and regulatory agencies around the world have stringent regulations for cosmetics. In the United States, cosmetic products and ingredients do not require FDA approval, although marketed products are monitored for safety. Some countries have banned using animal testing for cosmetics.

The word cosmetics is derived from the Greek κοσμητικὴ τέχνη (kosmetikē tekhnē), meaning "technique of dress and ornament," from κοσμητικός (kosmētikos), "skilled in ordering or arranging," and from κόσμος (kosmos), meaning "order" and "ornament.".

Though often referred to socially as makeup, cosmetics technically include substances used to clean or alter the complexion, skin, hair, or teeth -- placing eye shadow, teeth-whitening strips, and perfumes under the same umbrella.

In the United States, the Food and Drug Administration (FDA), which regulates cosmetics, defines cosmetics as products "intended to be applied to the human body for cleansing, beautifying, promoting attractiveness, or altering the appearance without affecting the body's structure or functions." This broad definition includes any material intended for use as an ingredient in a cosmetic product, with the FDA specifically excluding pure soap from this category.

Cosmetics designed for skin care may be used to cleanse, exfoliate and protect the skin, as well as replenish it, using body lotions, cleansers, toners, serums, moisturizers, eye creams, retinol, and balms. Cosmetics designed for more general personal care, such as shampoo, soap, and body wash, can be used to clean the body.