Kidneys are internal organs, which are a part of the urinary tract of animals. They are classified as offal. The tissue in the kidneys is compacted, firm and quite hard. The surface of meat can be moist and glossy. Kidneys are surrounded by a perinephric fatty tissue. Beef kidneys are characterized by a dark red colour and a slight hypertrophy of fatty tissue. Kidneys provide large amount of high-valued protein, vitamin A and vitamins B. They have a low fat level and small amounts of cholesterol. They are used in soups, stews, cans, sausages, pâtés and roulades.