Shampoo is a kind of hair care product, which is usually used to clean hair in the form of viscous liquid. Less commonly, shampoo is provided in the form of soap, such as soap. The way to use shampoo is to apply it on wet hair, massage the product into the hair, and then rinse it. Some users may use conditioner to wash their hair.

The purpose of using shampoo is to remove the excess accumulation on the hair without peeling off too much sebum, which makes the hair difficult to handle. Shampoo is usually made by mixing surfactants (most commonly sodium dodecyl sulfate or sodium dodecyl sulfate) with cosurfactants (most commonly cocamidopropylbetaine) in water.

Children with dandruff, hair dye, gluten or wheat allergy who are interested in using "natural", "organic", "plant" or "plant-based" products can use special shampoo. ("baby shampoo" is less irritating). There are also shampoos for animals that may contain pesticides or other drugs to treat skin conditions or parasites (such as fleas).

A shampoo is usually prepared by mixing a surfactant (usually sodium dodecyl sulfate or sodium dodecyl sulfate) with a cosurfactant (usually cocamidopropyl betaine) in water to form a viscous liquid. Other essential ingredients include salts (sodium chloride), preservatives and spices used to regulate viscosity.