Ducks are waterfowl belonging to the family Anatidae, which also includes geese and swans. There are over 120 species of ducks worldwide, varying in size, color, and habitat. Common species include the mallard, wood duck, and northern pintail. Ducks can be found in both freshwater and saltwater environments, often inhabiting ponds, lakes, rivers, and marshes. Ducks are known for their distinctive quacking sounds, although not all species quack. They are omnivorous, feeding on a diet of aquatic plants, insects, and small fish. Many duck species are migratory, traveling long distances between breeding and wintering grounds, while others are resident birds that stay in the same area year-round.