The duck is a number of species in the Anatidae family of birds. They are related to swans and geese.
Duck is the common name for numerous species in the waterfowl family Anatidae which also includes swans and geese. Ducks are divided among several subfamilies in the family Anatidae; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered ducks.