An airline, rail or shipping company may book more customers onto a vehicle than can actually be accommodated by an aircraft, train or cruise ship. This allows them to have a (nearly) full vehicle on most runs, even if some customers miss the trip or don't show up (tickets are often rebookable afterwards). Such customers are called no-shows.[1] If everyone shows up, at least in the case of airlines, the overbooking will cause an oversale.