Boiling is the cooking of prepared foods in a liquid at boiling point. This could be water, court bouillon, milk or stock. There are two ways of boiling: place food into boiling liquid, reboil, and then reduce the heat for gentle boiling to take place. Cover the food with cold liquid, bring to the boil, then reduce the heat and simmer. The advantages are that: older, tougher, cheaper joints of meat and poultry can be made palatable and digestible; it is appropriate for large-scale cookery; it is economic on fuel; nutritious, well flavored stock is produced; it is labor saving, as it requires little attention; and it is safe and simple and maximum color and nutritive value are retained when cooking green vegetables, provided boiling time is kept to the minimum.