A passenger airline is an airline dedicated to the transport of passengers. Passenger airlines usually operate a fleet of passenger aircraft which, rather than being owned outright, are usually leased from commercial aircraft sales and leasing companies.
There are several types of passenger airlines, mainly
Charter airlines, operating outside of regular schedule intervals
Flag carriers – The historically nationally owned airlines that were considered representative of the country overseas.
Legacy carriers – US carriers that predate the Airline Deregulation Act of 1978
Major airlines of the United States – Airlines with at least $1 billion in revenues.
Low-cost carriers, giving a "basic", "no-frills" and perceived inexpensive service
Mainline airlines operate flights by the airline's main operating unit, rather than by regional affiliates or subsidiaries.
Regional airlines, non-"mainline" airlines that operate regional aircraft. Regionals typically operate over shorter non-intercontinental distances, often as feeder services for legacy mainline networks.
Business class airline – An airline aimed at the business traveler, featuring all business class seating and amenities.