A regulation feather badminton shuttlecock has 16 feathers.
The feathers are arranged evenly around a cork base and secured so that the shuttle remains stable in flight. The cork is commonly covered with a thin layer of leather or another suitable material. Feather shuttles are valued for their flight characteristics, especially in high-level competition, although they are more fragile than synthetic alternatives.
The feathers traditionally come from the left wing of a goose or duck, because matching feathers can produce more consistent aerodynamic behavior. This detail is often remembered incorrectly as a requirement for every casual shuttlecock; plastic or synthetic shuttles are also widely used for recreational play.
A shuttlecock is not a ball. Its open feathered skirt creates substantial drag, causing the shuttle to slow rapidly after being struck. The Laws of Badminton specify the number of feathers and other construction details for approved feather shuttles.