The document defines several common terms used in air travel, including commercial flight, red-eye flight, and flight attendants. It describes the differences between military and civil aviation as well as domestic, international, non-stop, direct, and connecting flights. It also discusses various flight itineraries like one-way, open-jaw, round trip, and circle flights. Finally, it outlines classes of service on flights like first class, business class, and economy class as well as how seats are assigned.