“Old MacDonald Had a Farm” (sometimes shortened to Old MacDonald) is a traditional children’s song and nursery rhyme about a farmer and the various animals he keeps. Each verse of the song changes the name of the animal and its respective noise. For example, if the verse uses a cow as the animal, then “moo” would be used as the animal’s sound. In many versions, the song is cumulative, with the animal sounds from all the earlier verses added to each subsequent verse. The song was probably written by Thomas d’Urfey for an opera in 1706, before existing as a folk song in Britain, Ireland and North America for hundreds of years in various forms then finally being standardised in the twentieth century.