On aircraft, the cabin is the section of the aircraft in which passengers travel. Cabins in an aircraft are pressurized to maintain a normal breathing environment at cruising altitude.
Cabins may be divided by a wall (bulkhead) or curtain between different travel classes. First class passengers will sit in the first class cabin, while standard economy passengers sit in the main cabin.
On a ship, a cabin is a section in a ship or boat usually referring to the room where a passenger sleeps.
On a train or other type of transportation, the cabin is a sleeping compartment, such as those on a couchette.