The big air carriers know that any time they have a plane in the air with empty seats, they are losing money.
It might be obvious, but it is true that the airlines are motivated to be sure that every seat is sold in order to cover their cost of getting the plane off the ground and making a profit.
It is this very factor that creates the offers for discount airfares that people love to find for their flights from here to there, and back again.
Discounted flights are most often found through either travel agencies, which are also eager to gain more new clients and will work hard to find cheap fares for them, or through the reservation system of the airline itself.
In fact, some of the airlines offer discounted ticket prices that are only available directly through them on their website.
These are often referred to as "web only" discount tickets.
There are some travel experts who say that discount airfares for those last minute flights can save people as much as 75% over the price of a regular ticket.
But there is a danger in waiting until the last minute and trying to grab the cheapest airfares available.
The danger is that if you wait too long, then there might not be a seat available at all for the flight you need.
And, that's the rub when it comes to finding the cheapest, discounted airfares.
Sometimes you can find terrific deals on last minute flights that almost makes it seem like the airline is giving away their air tickets.
At other times, you may find that every last seat on every airline is booked and even if there was a seat, the demand is so high that there are no discounts to be found.
Being able to find discounted airfares has a great deal to do with when you travel.
If you need to fly when everyone else does because of a major holiday, such as Thanksgiving, Christmas or Spring Break, then you will get the best discount by booking as early as possible.
If you are traveling during other times and you can be flexible about your flight dates, then you will have a better chance of being able to grab deeply discounted fares.
There are some travelers who enjoy the excitement and thrill of hunting for those extreme discount airline tickets that are sometimes available for last minute flights.
They enjoy sitting down at the computer and seeing what airfare deals are available so they can get out of town for a few days.
For them, the exact destination is less important that the thrill of kicking back with spur-of-the-moment cheap vacations that they might not be able to afford to take otherwise.
Those who have the constitution for last minute bookings are generally very experienced travelers who have flexible schedules and who can make quick decisions.
They also either always have a bag packed and ready to go, or are able to throw a few things into a suitcase and be our the door and to the airport in under an hour from the time they land their discounted flight deals.
However, last minute travel is not something that can be undertaken by everyone and is particularly not well-suited for families or for groups of more than two.
Many times, these discount airfares are only available for one or two seats left on any particular flight.
But for those traveling alone or with one travel companion and who enjoys spur-of-the-moment travel, without the planning aspect, then taking advantage of last minute flights and discounted fares can make for many memorable cheap vacations which might not happen otherwise.