Swans belong to the family Anatidae, subfamily Anserinae, and genus Cygnus.

They are large waterfowl with a graceful appearance. Swans are characterized by their pure white plumage, long necks that exceed or are equal to their body length, a high base and gently sloping front of the beak, exposed eye gland, short and rounded tails with approximately several dozen tail feathers, powerful webbed feet,

The absence of webbing on their hind toes.

Swans are distributed across continents, except in Africa and Antarctica, and they mainly inhabit large lakes or marshy areas with abundant aquatic vegetation. They are migratory birds, flying in flocks from the south to the north for breeding between March and April each year.

After October, they migrate south again, wintering in warmer climates. Swans often fly in small groups of six to twenty, accompanied by calls, and exhibit high-speed flight. Their diet includes insects, mollusks, fish, frogs, clover, grains, and weeds.

Mature swans, typically around four years old, form lifelong pair bonds. Courtship behavior involves beak touching and head-to-head gestures. The female swan is responsible for incubating the eggs, while the male stands guard nearby. Some species may also have males taking turns in incubation. The cygnets, or young swans, have short necks and dense down feathers, and they can run and swim shortly after hatching.

Swans can live up to 20 years in the wild, while those in captivity can exceed 50 years. Due to their heavy bodies, swans must run a distance on water or land before taking flight.

Swan couples remain devoted to each other for life and are highly protective of their nests, eggs, and offspring, even engaging in fierce battles with predators such as foxes. Swans reach sexual maturity at 3 to 4 years old, and they reproduce annually, laying 4 to 6 large eggs per clutch. The incubation period lasts 35 to 40 days, and the male swan may also participate in incubation.

Swans display rich courtship behaviors, with the male and female performing synchronized movements and engaging in mutual preening.

During breeding, they primarily inhabit open lakes, ponds, marshes, slow-flowing rivers, and adjacent tundra lowlands and marshy areas. In winter, they prefer large lakes, reservoirs, ponds, and river estuaries with abundant reeds, bulrushes, and other aquatic plants, and they may also be found in wet grasslands, flooded plains, beaches, and coastal areas.

The story of Helen and Troy is well-known, and Helen's mythological origin has a touch of Western mythology: Zeus, the king of the gods, was enamored with the beauty of Sparta's queen, Leda. Transforming into a swan, Zeus seduced Leda, resulting in the birth of two golden swan eggs. One egg hatched Castor and Pollux, the twin Greek heroes, while the other hatched Leda's daughter, Helen. In mythology, the swan becomes a surrogate for the gods.

Using a swan as a divine form raises the question of why Zeus chose this particular transformation. Swans have been recognized early on in both Eastern and Western cultures on the Eurasian continent. Their pristine white feathers and graceful posture symbolize purity, elegance, and nobility. In Greek mythology, swans hold various roles, such as being the sacred bird of Hera, the queen of the gods, and the divine bird of Apollo, the sun god.

In the eyes of Westerners, swans are not ordinary birds; they possess angelic qualities. Imagining angels based on the swan's physique—mighty wings, sleek white feathers, and an elegant and noble demeanor—they are seen as a link between humans and gods. Angels surround the feet of gods, playing multiple roles, including Cupid, the god of love, and Apollo, the sun god associated with music, poetry, and art. Thus, the swan serves as a metaphor for literature and art.