AbstractEmulsions are complex systems frequently encountered in our daily lives and in most industrial sectors, including the oil industry. An understanding of the mechanisms of emulsion formation is essential both to create them and to treat them. The present work describes the main phenomena that come into play in emulsifying. The break‐up of droplets in either laminar or turbulent flow is discussed, and certain correlations, from which the diameter of the droplets formed can be predicted, are given. The role of surfactants is also examined, as are the typical time scales of the various processes involve