A regulation feather badminton shuttlecock traditionally uses 16 feathers inserted into its cork base.
The feathers form a cone around the rounded cork and are secured with thread and adhesive. Goose feathers are commonly preferred for high-quality tournament shuttlecocks because their structure provides consistent flight and durability. Manufacturers often select feathers from the same wing so the shuttlecock behaves more uniformly in the air.
The shuttlecock's unusual flight is central to badminton. It travels quickly after a smash but slows dramatically because its feathered skirt creates substantial drag. It also tends to orient its cork base toward the direction of travel, allowing players to strike the cork with the racket strings.
Plastic or nylon shuttlecocks are widely used for recreational play and training. They imitate the shape and flight of feather shuttlecocks but do not have 16 natural feathers. That distinction is why the answer applies specifically to the traditional feather type used in serious competition.