Aviation is a complex, strategic human activity that refers to the flight (navigation) of aircraft within the Earth's atmosphere (airspace). The English word aviation comes from the Latin word avia or aero.Aircraft engaged in flight activities, also known as aircraft, are divided into two categories: lighter-than-air aircraft and heavier-than-air aircraft. The former, such as balloons, airships, etc. , take off by aerostatic buoyancy; the latter, such as airplanes and helicopters, take off by aerodynamic force. Aviation is a complex and strategic human activity. It refers to the flight (navigation) activities of aircraft in the Earth's atmosphere (airspace), as well as scientific research and education, industrial manufacturing, public **** transportation, professional operations, air sports, national defense and military, government administration and other related fields. Through the use of airspace and aircraft (airplanes), aviation activities can be subdivided into many separate industries and fields, such as aeronautical manufacturing, civil aviation and so on. We can often see people using the term from their respective fields with rich and varied connotations. Aircraft engaged in flying activities, also known as aeronautical vehicles, are divided into two main categories: lighter-than-air aircraft and heavier-than-air aircraft. The former depends on the static buoyancy of the air, as in the case of balloons, airships, etc., while the latter depends on the aerodynamic force generated by the relative motion with the air, as in the case of airplanes and helicopters. According to whether or not manned, can be divided into manned aircraft and unmanned aircraft.