An aircraft cabin is the section of an aircraft in which passengers travel. At cruising altitudes of modern commercial aircraft, the surrounding atmosphere is too thin for passengers and crew to breathe without an oxygen mask, so cabins are pressurized at a higher pressure than ambient pressure at altitude.
In commercial air travel, particularly in airliners, cabins may be divided into several parts. These can include travel class sections in medium and large aircraft, areas for flight attendants, the galley and storage for in-flight service. Seats are mostly arranged in rows and alleys. The higher the travel class, the more space is provided. Cabins of the different travel classes are often divided by curtains, sometimes called class dividers, but not on all airlines. Passengers are not usually allowed to visit higher travel class cabins in commercial flights.
Some aircraft cabins contain passenger entertainment systems. Short and medium haul cabins tend to have no or shared screens whereas long and ultra-long haul flights often contain personal screens which allow passengers to choose what to watch on their personal screen.
Economy class is the airline travel class with the lowest ticket price, as the level of comfort is lower than that of the other classes. This class is primarily characterized by the short distance between each seat, and a smaller variety of food and entertainment.