A wind tunnel is a tool used to study the effects of air moving over objects. It creates a controlled environment where engineers and scientists can test how air flows around different shapes, such as cars, airplanes, and buildings. By observing the airflow, they can improve designs for better performance and efficiency. Wind tunnels can vary in size and design, from small models used in laboratories to large facilities that can accommodate full-scale vehicles. They are essential in fields like aerospace engineering, where understanding aerodynamics is crucial for the safety and effectiveness of aircraft and spacecraft, including those designed by companies like NASA and Boeing.