What is the purpose of winglets on an aircraft's wings?

The purpose of winglets on an aircraft's wings is to decrease drag. Winglets are vertical extensions at the tips of the wings that help to mitigate the formation of vortices, which occur as high-pressure air from the underside of the wing spills over to the low-pressure area on the top side. This vortex formation is a significant source of induced drag, which can reduce the efficiency of the aircraft.

By decreasing this drag, winglets enhance the overall aerodynamic efficiency of the aircraft. This results in better fuel economy and improved performance during flight, allowing the aircraft to maintain lift without requiring additional thrust. Consequently, the inclusion of winglets is a common design feature in modern aircraft aimed at improving performance and reducing operational costs.