When water & oil are mixed together & vigorously stirred a dispersion of oil droplets in water & vice versa is formed. When Stirring stops, the phases start to separate. However, when an emulsifier is added to the system, the droplets remain dispersed, & a stable emulsion is obtained. An emulsifier consists of a water loving hydrophilic head & an oil loving hydrophobic tail. The hydrophilic head is directed to the aqueous phase & the hydrophobic tail to the oil phase (see figure 1). The emulsifier Positions itself at the oil/water or air/water interface &, by reducing the surface tension, has a stabilising effect on the emulsion.