If one word could sum up the cosmetics industry, one word that the majority of cosmetic and toiletries could not do without, then that word is ‘surfactant’. It is the basis of all cleansing products, it is responsible for the structure of creams and lotions. This chapter concentrates on its use in cleansing products by describing how it can turn water into an effective cleansing product. We will learn how we build on that simple addition to give a huge range of products that are now available and how the science of surfactants is adapting with current trends of natural, organic and sustainability.