The primary source of induced drag is the wing, as it is the main lift-generating surface of the aircraft. When the wing generates lift, it creates a pressure differential between the upper and lower surfaces. This pressure difference causes air to move from the high-pressure area below the wing to the low-pressure area above it, especially near the wingtips, forming wingtip vortices.

These vortices create a swirling flow pattern that results in downwash behind the wing. The downwash alters the effective angle of attack along the wingspan, causing an additional rearward component of aerodynamic force known as induced drag.