An emulsion is a mixture of two immiscible liquids, typically oil and water, that are held together by an emulsifying agent.
Emulsions can be divided into two types: oil-in-water (where oil droplets are dispersed in water) and water-in-oil (where water droplets are dispersed in oil).
The emulsifying agent helps to stabilize the mixture by breaking the surface tension between the two liquids and keeping them in a state of suspension. Common emulsifiers include egg yolks, lecithin, mustard, and mono- and diglycerides.
Emulsions have many practical applications, such as in food production (mayonnaise, salad dressings, and ice cream), cosmetics (lotions, creams, and makeup), and pharmaceuticals (ointments and creams).
Emulsions can be affected by a variety of factors, such as temperature, pH, and agitation. If the emulsion becomes unstable, the liquids will separate, causing the product to lose its desired texture and appearance.