Aeronautics is the science or art involved with the study, design, and manufacturing of air flight capable machines, and the techniques of operating aircraft and rockets within the atmosphere. The British Royal Aeronautical Society identifies the aspects of "aeronautical Art, Science and Engineering" and "the profession of Aeronautics (which expression includes Astronautics)." While the term originally referred solely to operating the aircraft, it has since been expanded to include technology, business, and other aspects related to aircraft. The term "aviation" is sometimes used interchangeably with aeronautics, although "aeronautics" includes lighter-than-air craft such as airships, and includes ballistic vehicles while "aviation" technically does not.
Aerospace engineering is the primary field of engineering concerned with the development of aircraft and spacecraft. It has two major and overlapping branches: Aeronautical engineering and Astronautical Engineering. Avionics engineering is similar, but deals with the electronics side of aerospace engineering. Aeronautical engineering was the original term for the field. As flight technology advanced to include craft operating in outer space (astronautics), the broader term "aerospace engineering" has come into common use. Aerospace engineering, particularly the astronautics branch, is often colloquially referred to as "rocket science".