Dairy is a catch-all term for food and drink products that are made from the milk of mammals. Cows are the main mammal from which dairy products are made, but sometimes, goat's milk can be used instead.
Dairy products are known for being high in complete protein, fat (though the fat can be reduced or removed in processing), the sugar lactose (which many humans do not tolerate well), and other nutrients.
Examples of dairy products include milk itself, cheese, yogurt, cottage cheese, and kefir.