Taking into consideration cancellation and no-shows, airlines have always been overbooking flights in order to maintain a full flight and keep the prices low. Most of the time, predictions are accurate and all passengers are able to board the flight. However, on some occasions, passengers will be "bumped". Bumping also referred to as "declined-boarding", is when passengers are forced to give up their seats involuntarily. Before bumping passengers, airlines must first ask for volunteers in exchange for compensation. When there aren't enough volunteers, bumping takes place.