Surfactants or surface active agents are wetting agents that lower the surface tension of liquids allowing easier spreading of liquids, dispersion of solids, inhibition of foam and emulsification of mixtures. Surfactants are usually amphipathic organic molecules, i.e., containing both hydrophobic and hydrophilic groups, making them slightly soluble in both organic solvents and water. They can be anionic, cationic or amphoteric (both positively and negatively charged). These detergent properties enable them to emulsify oils and suspend dirt so that they can be washed away with water. Surfactants are also used in cosmetic preparations to allow lotions and cosmetic liquid to quickly and evenly spread on the skin.