First class is a travel class on some passenger airliners intended to be more luxurious than business class, premium economy, and economy class. On a passenger jetliner, first class usually refers to a limited number (rarely more than 20) of seats or cabins toward the front of the aircraft which have more space, comfort, service, and privacy. In general, first class is the highest class offered, although some airlines have introduced new classes above this. Propeller airliners often had first class in the rear, away from the noise of the rotating propeller.