Mayonnaise, informally "mayo," is a thick cold condiment or dressing usually used in sandwiches and composed salads or on chips. It is a stable emulsion of oil, egg yolk, and acid, either vinegar or lemon juice. There are many variants using additional flavorings. The proteins and lecithin in the egg yolk serve as emulsifiers in mayonnaise (and hollandaise sauce). The color of mayonnaise varies from near-white to pale yellow, and its texture from a light cream to a thick gel. It is also a base in sauces such as Tartar sauce.