Or last minute buys. You can never be sure of the final result. If the company has already sold enough tickets and the plane is nearly full, they will sell off tickets at expensive prices. Or vice versa, if the plane is almost empty, the flight tickets can be very cheap at the last minute.It does depend on the destination and the company though. It's up to you if you feel you can negotiate a price at the last minute at the airport.
However, the reduction may be up to 50% off the full price, but there is no guarantee of a return on a given date. You'll have to wait until there are seats available on the plane, unless you pay a supplement, which then cancels out the savings you made on the outgoing flight.
This system is called standby and it has to be said that it is a system that is practically obsolete. There once was a similar formula that existed called J-1 (reduced-price tickets could be purchased the night before the departure), but this no longer exists. The only people who regularly benefit from standby flights are personnel of the companies.
This formula practically no longer exists because companies find it hard to believe that someone who is buying their ticket last minute has other options, which means he would be prepared to pay a full price ticket.
It is nevertheless possible to purchase tickets at the airport for airlines that have a sales counter (which is the case for the big companies). However, it is best to decide which company you want to go with ahead of time or you will spend your time moving from one counter to another, some of which are not always in the same terminal. The rates are the same as the ones published on the company's website, except in the cases of special Internet offers.