Frequent-flyer programs in the context of "Passenger flight"

An airline is a company that provides a regular service of air transportation for passengers or freight (cargo). Airlines use aircraft to supply these services. Many passenger airlines also carry cargo in the belly of their aircraft, while dedicated cargo airlines focus solely on freight transport. Generally, airline companies are recognized with an air operating certificate or license issued by a governmental aviation body. Airlines may be scheduled or charter operators.

Airline ownership has seen a shift from mostly personal ownership until the 1930s to government-ownership of major airlines from the 1940s to 1980s and back to large-scale privatization following the mid-1980s. Since the 1980s, there has been a trend of major airline mergers and the formation of partnerships or alliances for codeshare agreements, in which they both offer and operate the same flight. The largest alliances are Star Alliance, SkyTeam and Oneworld. Airline alliances coordinate their passenger service programs (such as lounges and frequent-flyer programs), offer special interline tickets and often engage in extensive codesharing (sometimes systemwide).