What ingredient in shampoo primarily serves to enhance lathering?

Surfactants are the key ingredient in shampoo that enhances lathering. These compounds lower the surface tension of water, allowing it to spread and penetrate more easily. This action helps in creating a rich foam as the shampoo is mixed with water and agitated. Surfactants work by binding to both water and oil, allowing dirt and grease to be washed away effectively, which contributes to the lathering process that consumers often associate with the effectiveness of a shampoo.

Other ingredients like moisturizers and emollients serve to hydrate and soften hair but do not contribute to lather formation. Thickeners may adjust the viscosity of the product but also do not play a direct role in lather enhancement. Therefore, surfactants are crucial for the cleaning action and the desirable lather effect in shampoos.