An emulsion is a mixture of two liquids that usually do not mix well, such as oil and water. In an emulsion, tiny droplets of one liquid are dispersed throughout the other, creating a stable blend. Common examples include mayonnaise and salad dressings, where oil is mixed with vinegar or lemon juice. Emulsions can be classified into two main types: oil-in-water (O/W) and water-in-oil (W/O). In O/W emulsions, oil droplets are dispersed in water, while in W/O emulsions, water droplets are dispersed in oil. Emulsifiers, such as lecithin or soap, help stabilize these mixtures by reducing the surface tension between the liquids.