Fletching is the ancient art of creating arrows from materials such as wood and feathers. As a noun, fletching refers to the fins attached to an arrow; traditionally, this consists of three matched half-feathers attached near the back of the arrow's shaft, and equally spaced around its circumference.
More generally, it can refer to any structures added to a projectile in order to aerodynamically stabilize its flight, many of which resemble arrows in form and function. For instance, the feathers at the butt end of a dart (missile) (of the type cast using an atlatl) are very similar in purpose and construction to those used in arrows. Most of the techniqes of fletching were likely adapted from earlier dart-making techniques.