An aircraft cabin is the section of an aircraft in which passengers travel, often just called the cabin. At cruising altitudes, the surrounding atmosphere is too thin to breathe without an oxygen mask, so cabin pressurization adapts the cabin to atmospheric pressures. 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. Passengers are not usually allowed to visit another travel class cabin in commercial flights.
