overbooking" defined by the U.S department of transportation. "Overbooking is the practice of selling more tickets on an airplane than there are seats. Airlines benefit from flying full airplanes, which is more profitable than flying with some seats left empty. Since a few passengers often fail to make their flights, overbooking mitigates the risk of empty seats. This helps the airline keep fares lower and provide more flexibility to passengers. Instead of solely selling draconian “take the flight you booked or lose all of your money” trips, airlines provide passengers with an array of options.
