Egg yolks are the nutrient-dense central portions of eggs surrounded by the whites, composed of water, lipids, proteins, and micronutrients including fat-soluble vitamins, choline, and carotenoid pigments that give the characteristic golden colour. Their lecithin-rich lipoproteins make them outstanding natural emulsifiers, the foundation of mayonnaise, hollandaise, and countless bakery creams, while their proteins coagulate on heating to thicken custards and sauces. Colour intensity reflects the hen’s diet, particularly carotenoid content, and is a graded quality attribute. Like all egg components they carry Salmonella risk when raw, so pasteurized yolk products serve applications where safety cannot be left to chance.