An emulsion is a temporarily stable mixture of two immiscible fluids, one of which (dispersed phase) is dispersed in the other (dispersing phase) in the form of droplets.

This is the result of two or more liquids that, when shaken, are not homogeneously mixed (the two phases can be distinguished even after mixing). The emulsion is therefore a particular heterogeneous mixture.

Its stability depends on several elements but, in general, the most important are the density of the two phases, the temperature, the presence of surfactants (emulsifiers) and electrolytes.

Suspensions, unlike emulsions (that are mixtures consisting of two fluids) involve a liquid phase and a solid phase: a predominant liquid dispersing phase and minor dispersed solid phase.