Aerodynamic drag is the resistance an object encounters as it moves through a fluid, such as air. This force opposes the motion of the object, making it harder to move faster. The amount of drag depends on factors like the object's shape, speed, and the density of the fluid. In vehicles like cars and airplanes, reducing aerodynamic drag is crucial for improving fuel efficiency and performance. Engineers often design these vehicles with streamlined shapes to minimize drag. Understanding aerodynamic drag is essential in fields like aerospace engineering and automotive design.