An emulsifier is a substance that helps mix two liquids that usually do not blend well, such as oil and water. It works by reducing the surface tension between the liquids, allowing them to combine into a stable mixture called an emulsion. Common examples of emulsifiers include lecithin, found in egg yolks, and monoglycerides, often used in processed foods. Emulsifiers are widely used in the food industry to improve texture and shelf life. They can be found in products like mayonnaise, salad dressings, and ice cream. In addition to food, emulsifiers are also used in cosmetics and pharmaceuticals to create stable formulations.