Air travel$ Air travel is a form of traveling using an airplane.The comfort on traveling by air depends on several factors starting with the airport, the choice of the airline and the travel class.Travel class on an airplane is usually split into a two or four class model. National flights usually have two classes: economy Class cabin and business class cabin, whereas long haul flights usually have four classes: an economy class cabin, a premium economy cabin, a business class or a club class cabin and finally, a first class cabin.With the differences between premium economy and economy being moderately significant, the cost is not greatly altered upon purchase of a premium Economy ticket. The price of an economy class ticket and a first class ticket are often extremely different, with prices for a first class ticket being at least $1700 (£850) more expensive. The difference between standard Class and first Class when travelling by rail is often not as expensive, but tickets $1200 (£600) more expensive are not uncommon.Any air travel starts and ends at a commercial airport. The typical procedure is check-in, border control, airport security check of baggage and passengers before entering the gate, boarding, flying and pick-up of luggage and - limited to international flights - another border control at the host country border.A travel class is a quality of accommodation on public transport. The accommodation could be a seat or a cabin for example. Higher travel classes are more comfortable and more expensive. Airlines:-A typical wide-body jet plane seat plan (Asiana Boeing 747-400) .Economy class cabin , Business class cabin , First class cabinAirlines traditionally have three travel classes (although many airlines are eliminating first class from international fights and offering business class as the highest level of service):First Class, the highest quality and most exclusive of accommodation available (not available internationally on all US-based carriers except for American Airlines and United Airlines and many foreign carriers). Business Class, high quality, traditionally purchased by business travellers (sometimes called executive class), and the highest level of international service on many airlines Premium Economy, slightly better Economy Class seating (greater distance between rows of seats; the seats themselves may or may not be wider than regular economy class) Economy Class (also known as coach class or travel class), basic accommodation, commonly purchased by leisure travellers Three-cabin configuration is usually found only on international flights, though they are also found on transcontinental flights. For shorter distances, most airlines fly a two-cabin plane, featuring only Business and Economy Class cabins. The short-haul Business Class cabin is usually designated as "First Class" in North America (domestic).Some airlines merge their international First and Business classes into a premium business product with the consequence of lost exclusivity (for example, Continental Airlines have a BusinessFirst class), whereas others supplement the Business Class cabin with a Premium Economy class cabin. Some flights operated by Singapore Airlines (using their Airbus A340-500 aircraft) offer only Business and Premium Economy Class service. Some airlines, such as Japan Airlines and Lufthansa, offer flights with only a Business Class service.Most low-cost carriers and regional affiliates of major carriers only provide an Economy Class. The costs of extra services and amenities afforded to the premium cabins is eliminated, and more seats can be installed on an aircraft. Fare class:-Within each travel class there are often different fare classes, relating to ticket or reservation restrictions and used to enhance opportunities for price discrimination. Passengers within the same travel class receive the same quality of accommodation and may indeed sit next to each other; however, the price or restrictions they face for that accommodation will vary depending on the fare class. Fare classes may also vary by how far ahead the ticket must be purchased, or how long the length of stay is. For example, full fare economy class passengers (booking code Y) are usually able to make changes to their reservation, while discount economy class passengers in the lowest booking code usually have tickets that are non-refundable, non-upgradeable, non-transferable, or non-changeable without a hefty fee. Airline fare classes are commonly indicated by letter codes, but the exact hierarchy and terms of these booking codes vary greatly from carrier to carrier. First class codes:-F, A, P, R On domestic flights, F commonly indicates first class on a two-cabin plane. If a three-cabin aircraft is used, P (for "premium") may be used to distinguish the higher level of service in first class. The R code indicated supersonic transport and was no longer used after the retirement of the Concorde, however with the introduction of the new Airbus A380, Singapore Airlines has re-introduced the R class to distinguish their "Singapore First Suites" as a higher class than regular First Class. The A and Z codes may indicate a first class ticket whose fare is reduced due to restrictions on refunds, advance reservation requirements, or other terms.