Disodium decyl phenyl ether disulfonate is a substance used in cosmetic formulations. The substance acts as a surfactant, detergent, and emulsifier (changes the interfacial tension of liquids like water and oil so that they can be mixed together). Disodium decyl phenyl ether disulfonate continues to act hydrotropically (increases the solubility of a substance which is hardly soluble in water).
An "ether" is a linking product (condensation product) of two alcohols. The simplest ether is dimethyl ether (CH3-O-CH3).
The term decyl describes an alkyl group with the molecular formula C10H21, which occurs as a functional group within the molecule.