A wing is a fin designed to produce both lift and drag as it moves through air, with its efficiency often measured by the lift-to-drag ratio. Derived from the Old Norse word vængr for bird limbs, the term "wing" has expanded in recent centuries to include lift-generating appendages on everything from aircraft and insects to boomerangs and race cars. Aerodynamics, the science behind wing performance, explains that lift is primarily created when a wing is oriented at a suitable angle of attack, deflecting airflow downwards. This action generates lower air pressure above the wing and higher pressure below it, resulting in an upward force, a concept explained partly by Bernoulli's principle. While asymmetrical cross-sections are common, symmetrical wings are also used, notably in aerobatic aircraft, to ensure consistent flight characteristics whether upright or inverted.