Aviation pioneers are people directly and indirectly responsible for the advancement of flight, including people who worked to achieve manned flight before the invention of aircraft, as well as others who achieved significant "firsts" in aviation after heavier-than-air flight became routine. Pioneers of aviation have contributed to the development of aeronautics in one or more ways: through science and theory, theoretical or applied design, by constructing models or experimental prototypes, the mass production of aircraft for commercial and government request, achievements in flight, and providing financial resources and publicity to expand the field of aviation.