Air travel

 Air travel is a form of travel in vehicles such as airplanes, jet aircraft, helicopters, hot air balloons, blimps, gliders, hang gliders, parachutes, or anything else that can sustain flight. Use of air travel began vastly increasing in the 1930s: the number of Americans flying went from about 6,000 in 1930 to 450,000 by 1934 and to 1.2 million by 1938. It has continued to greatly increase in recent decades, doubling worldwide between the mid-1980s and the year 2000. Modern air travel is much safer than road travel.

Domestic and international flights

Air travel are separated into two general classifications: national/domestic and international flights. Flights from one point to another within the same country are domestic flights. Flights from a point in one country to a point within a different country are international flights. Travelers can use domestic or international flights in either private or public travel.

Commercial air travel

Travel class on an airplane is usually split into a two, three or four class model service. U.S. domestic flights usually have two classes: economy class and a domestic first class partitioned into cabins. International flights may have up to four classes: economy class; premium economy; business class or club class; and first class.

Most air travel starts and ends at a commercial airport. The typical procedure is check-in; border control; airport security baggage and passenger check before entering the gate; boarding; flying; and pick-up of luggage and – limited to international flights – another border control at the host country's border. Most passengers must go through these steps when flying with a commercial airline. 

For longer journeys, air travel may consist of several flights with a layover in between. The number of layovers often depends on the number of hub airports the journey is routed through.

Airlines rely either on the point-to-point model or the spoke-and-hub model to operate flights in between airports. The point-to-point model, often used by low-cost carriers such as Southwest, relies on scheduling flights directly between destination airports. The spoke-and-hub model, used by carriers such as American and Delta, relies on scheduling flights to and from hub airports. The hub-and-spoke model allows airlines to connect more destinations and provide more frequent routes, while the point-to-point system allows airlines to avoid layovers and have more cost effective operations.