Wing

A wing is an appendage or surface that enables or enhances lift. In biology, wings are appendages used for flight in many animals, notably birds, bats, and insects. In aviation and aerospace, a wing is the primary lifting surface of a fixed‑wing aircraft. In architecture, a wing refers to a separate division or extension of a building.

Biological wings vary widely. Birds have forelimbs modified into wings with feathers and muscles; the pectoralis major powers the downstroke while the supracoracoideus raises the wing. Bats use flexible skin membranes stretched between elongated fingers. Insects may have four wings or two, often sculpted of chitin and powered by indirect or direct flight muscles.

Aircraft wings function as lifting surfaces shaped as airfoils. They generate lift from air pressure differences created by their curved upper and flatter lower surfaces. Wing planforms include straight, swept, and delta shapes, with high, mid, or low mounting. Features such as dihedral, winglets, flaps, and slats influence stability and takeoff or landing performance.

In other contexts, "wing" denotes a subdivision of an organization or building. In military aviation, a wing is a unit comprising multiple squadrons. In politics and culture, it refers to a faction aligned on a spectrum (left wing, right wing).

Wings have evolved independently in several lineages and exhibit a range of adaptations from gliding membranes to rigid flight surfaces, reflecting different ecological demands and mechanical constraints.