What is the purpose of an airfoil?

An airfoil is designed primarily to generate lift as air flows over and under it. The shape of an airfoil is critical in creating a pressure difference between its upper and lower surfaces. As the aircraft moves through the air, the wing's design causes the air to travel faster over the top surface than over the bottom surface, resulting in lower pressure atop the wing and higher pressure underneath. This pressure difference is what generates lift, allowing the aircraft to ascend and remain airborne.

The other aspects associated with an airfoil include the reduction of drag and the stabilization of the aircraft, but these functions are secondary to the primary role of lift generation. While a well-designed airfoil can also lead to reduced drag, its fundamental purpose is to create the necessary lift force required for flight. Similarly, stability during turbulence and weight reduction are important characteristics in aircraft design but do not define the core function of an airfoil itself.