Animals can be used as food either directly or indirectly by the products they produce. Meat is an example of a product directly derived from an animal, which comes from either muscle systems or organs. Food products derived from animals include milk produced by mammals, which in many cultures is drunk or processed into dairy products like cheese or butter. In birds and other animals that lay more eggs, which are often eaten, and bees produce honey, a popular sweetener in many cultures. Some cultures do not consume blood, sometimes in the form of blood sausage, as a thickener for sauces, a cured in brine for periods of food scarcity, and others use blood in stews such as civet.