An emulsion is a combination of oil and water, two substances which normally do not mix. An emulsion is achieved by suspending tiny droplets of the oil evenly in the water or other liquid to create what appears to be a uniformly smooth, creamy, thickened liquid. To emulsify something, the oil is gradually mixed into the water-based liquid, usually using a whisk, a food processor or a blender. An emulsifier is often used, which is a third substance that helps to combine the oil and water. This can be something like egg yolks, mustard or food-grade gums like xanthan.