Systems in which one type of particles is dispersed in another is referred to as a dispersion system. Their classification depends on the particle size. Colloids are a subtype of dispersion systems whose particle size range from 1 to 100 nm. One example of colloidal systems are emulsions in which one liquid is scattered in another. There are two types of emulsions; oil emulsions in water and water in the oil. Emulsion properties are determined by the size of the dispersed droplet, the composition and properties of the droplet surface layer and the composition of the continuous phase. Droplets in emulsions are generally spherical and subject to deformation. Some of the instability of emulsions are the separation of droplets on the surface, aggregation or coalescence. In order to create an emulsion and ensure its stability, emulsifiers are used. Emulsions are represented in the food industry. The aim of this paper is to define dispersion systems and colloid systems, to describe the classification of colloids and colloid properties, to define emulsions, creation of emulsions, phenomena on the liquid – liquid inteface, the effect of emulsifiers on emulsions and their stability. In addition, the aim is to present some examples of emulsions in the food industry.