Airplanes come in many different shapes and sizes. They play many different roles, in many different countries. Airplanes are used for commercial use by companies like MidWest Express. The US military use airplanes of many kinds. They also use bombers, an example of a bomber is the B-52.
Airplanes use areodynamics to make less drag and go faster.
They test the areodynamics, with planes, in a wind tunnel.