In aqueous solutions surfactants behave like organic compounds that are amphiphilic, meaning they contain both hydrophobic groups (their tails) and hydrophilic groups (their heads). The arrangement of the hydrophilic head is at the interface of water and the hydrophobic groups aligns toward oil. Therefore, a surfactant contains both a water-insoluble (or oil-soluble) component and a water-soluble component. Surfactants will diffuse in water and adsorb at interfaces between air and water or at the interface between oil and water, in the case where water is blended with oil. This property allows surfactants to act as detergents, wetting agents, emulsifiers, foaming agents, and dispersants.

Many important surfactants include a polyether chain terminating in a polar anionic group. The polyether groups often comprise ethoxylated (polyethylene oxide-like) sequences inserted to increase the hydrophilic character of a surfactant. Polypropylene oxides conversely, may be inserted to increase the lipophilic character of a surfactant. Surfactant molecules have either one tail or two; those with two tails are said to be double-chained. Surfactant classification according to the composition of their head falls under nonionic, anionic, cationic, and amphoteric. A nonionic surfactant has no charged groups in its head. The head of an ionic surfactant carries a net positive, or negative charge. If the charge is negative, the surfactant is more specifically called anionic; if the charge is positive, it is called cationic. If a surfactant contains a head with two oppositely charged groups, it is termed zwitterionic. Zwitterionic or amphoteric surfactants have both cationic and anionic centers attached to the same molecule.

Two major surfactants, are linear alkylbenzene sulfonates (LAS) and the alkyl phenol ethoxylates (APE). anionic surfactants contain anionic functional groups at their head, such as sulfate, sulfonate, phosphate, and carboxylates. Prominent alkyl sulfates include sodium lauryl sulfate (sodium dodecyl sulfate, SLS, or SDS), and the related alkyl-ether sulfates sodium laureth sulfate (sodium lauryl ether sulfate or SLES), and sodium myreth sulfate.