An emulsifier is an additive which helps two liquids mix. For example, equal amounts of water and oil when poured in a glass tend to separate after some time, but adding an emulsifier will help these liquids mix. This process of mixing two immiscible phases like oil and water using an additive to form one phase after mixing is called emulsification. Two liquids can form different types of emulsions. For example, oil and water can form, first, an oil-in-water emulsion, in which the oil is the dispersed phase, and water is the continuous phase. Secondly, when water is the dispersed phase and oil is the continuous phase they can form a water-in-oil emulsion (see Figure 1). Therefore technical explanation of the word emulsifier is applicable mostly when both phases, dispersed and continuous, are liquids. For solid emulsions/dispersions the term colloids is often used. Some natural examples of emulsifiers are egg yolks and mustard sauce.