An airline provides air transport services for passengers or freight, generally with a recognized operating certificate or license. Airlines lease or own their aircraft with which to supply these services and may form partnerships or alliances with other airlines for mutual benefit.
Airlines vary from those with a single airplane carrying mail or cargo, through full-service international airlines operating hundreds of airplanes. Airline services can be categorized as being intercontinental, intra continental, domestic, or international and may be operated as scheduled services or charters.