A landing fee is a charge paid by an aircraft to an airport company for landing at a particular airport. Landing fees can vary greatly between airports, with congested airports, ones where most of the landing slots are held by airlines being able to charge premium prices because of supply and demand, while less congested airports charge less because the demand is not as high. The money generated [1] by landing fees is used to pay for the maintenance or expansion of the airport's buildings, runways, aprons and taxiways.[2]