Air vehicles are machines designed for flight in the atmosphere. They include various types such as airplanes, helicopters, and drones. Air vehicles can be powered by engines or rely on lighter-than-air gases, like helium in hot air balloons. They are used for transportation, recreation, and military purposes. These vehicles operate based on principles of aerodynamics, which involve the movement of air around them. Wings generate lift, allowing airplanes to ascend, while rotors on helicopters provide vertical takeoff and landing capabilities. Air vehicles play a crucial role in connecting people and goods across vast distances.