Food additives are substances added to food during processing or packaging to preserve freshness, improve texture or flavor, or enhance appearance. They include preservatives, antioxidants, emulsifiers, colors, flavors, and more. Additives are classified as direct or indirect depending on whether they are intentionally added to a specific food. They serve various functions like maintaining nutrient value, controlling spoilage, and improving properties like texture, color and shelf life. Some common types of food additives are colors, flavors, sweeteners, preservatives, emulsifiers and thickeners.