"Old MacDonald Had a Farm" is a popular children's song that describes the various animals found on a farm. The song features Old MacDonald, a farmer, who has different animals, each making their own unique sounds. The repetitive structure makes it easy for children to sing along and learn about farm life. The song typically includes animals like cows, pigs, sheep, and ducks, with each verse highlighting a specific animal and its sound. This engaging format helps children develop language skills and encourages participation through singing and mimicking animal noises.