Milk is a white liquid produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals before they are able to digest other types of food. Early-lactation milk contains colostrum, which carries the mother's antibodies to its young and can reduce the risk of many diseases. Milk contains many other nutrients^[1] and the carbohydrate lactose. The majority of the world's population is lactose intolerant.^[2]

As an agricultural product, milk is extracted from mammals during or soon after pregnancy and is used as food for humans. Worldwide, dairy farms produced about 730 million tonnes of milk in 2011,^[3] from 260 million dairy cows.^[4] India is the world's largest producer and consumer of milk, yet neither exports nor imports it. New Zealand, the European Union's 28 member states, Australia, and the United States are the world's largest exporters of milk and milk products. China and Russia are the world's largest importers of milk and milk products.^[5][6]

Throughout the world, there are more than six billion consumers of milk and milk products. Over 750 million people live within dairy farming households.^[7]