White sauces fall into two categories: milk-based, often called béchamel, and stock-based or velouté. Both are based on a butter and flour roux, and the velouté is made with fish, poultry or veal stock.
White sauces offer the widest range of possibilities in the whole sauce repertoire. They are used to bind soufflés, croquettes and fritters, as a base for gratins, and to thicken soups as well as their more usual function of coating food. One reason for their versatility is the neutral background they offer to a wide range of flavorings, from wine and herbs to curry powder and capers.