shampoo

Shampoo is a hair care product designed to cleanse the scalp and hair by removing oils, dirt, and buildup. It typically forms a lather when mixed with water and is applied to wet hair, then rinsed away.

Most modern shampoos are water-based emulsions that use surfactants as cleansing agents. Common surfactants include anionic detergents such as sodium laureth sulfate, along with milder amphoteric or nonionic detergents. Shampoos may include conditioning agents (quaternary ammonium compounds, silicones), thickeners, preservatives, fragrances, and colorants. The pH is usually mildly acidic to near neutral, around 5 to 6, to match hair and scalp chemistry.

Variants include liquid shampoos and solid shampoo bars. Formulations are tailored for hair types and needs, such as clarifying shampoos for buildup, moisturizing or gentle sulfate-free shampoos for dry or color-treated hair, and scalp-specific versions. Application is typically to wet hair, massage into the scalp to create lather, rinse, and often follow with a conditioner.

The term shampoo derives from the Hindi word champo meaning to massage or knead. Modern formulations emerged in the 20th century with synthetic detergents replacing soap. Regulations vary by country and require ingredient labeling; manufacturers consider environmental impact, with some brands offering biodegradable ingredients or reduced packaging.