A cow is a large farm animal that provides milk, which humans use to make cheese, butter, yogurt, and countless other foods. Female cattle are called cows, while males are called bulls, and young cattle are called calves. When you drink a glass of milk or eat a slice of pizza, you're enjoying something that probably came from a cow.

Cows are ruminants, meaning they have special stomachs with four chambers that let them digest tough grass and hay that humans couldn't eat. They spend much of their day grazing in pastures, pulling up mouthfuls of grass with their tongues. A cow can eat about 40 pounds of food and drink a bathtub's worth of water each day.

People have raised cows for over 10,000 years, making them one of humanity's most important domesticated animals. Beyond milk, cows provide meat (called beef), and historically they pulled plows and wagons before tractors existed. In some cultures, cows are considered sacred and treated with special respect.

The phrase till the cows come home means for a very long time, since cows amble slowly back to the barn at the end of the day. If someone says you could wait till the cows come home, they mean you'd be waiting practically forever.