Almost every time you make an airline reservation, once you settle on a fare you agree to pay, comes the real challenge: choosing a seat.

Twenty years ago, the choices were relatively simple and uncomplicated. If you were flying economy, you could choose window or aisle, or if you booked early enough, an exit row seat. If families wanted to fly together, they could choose a whole row in the center of a wide-body aircraft.

But then, as airlines added more seats to their airplanes, they also looked to maximize additional revenue, and most airlines then assigned additional prices to those coach seats. And thus began the upsell of the airline seat.

Window and aisle seats carried an additional cost, ranging from $20 to more than $90 in some cases. Exit row seats can be had —- for a price. Extra leg room seats? Those will cost you, too. Even those dreaded middle seats closer to first or business class are considered premium seats simply because they’re closer to the exit, and can be purchased.

While some airlines — notably, Southwest — don’t charge for seats, many do because they can. It offers them a huge revenue stream that isn’t subject to high federal ticket taxes — another fee, just like checked baggage or buying a meal on board. And the airlines make more clear profit from these ancillary fees than they actually do from ticket sales. A report from airline ancillary strategy firm IdeaWorksCompany showed that airlines earned an average of $27.60 in ancillary revenue per passenger in 2021, which added up to total ancillary revenue of about $65.8 billion globally through that same period.

To complicate matters, how do you really know which seats — or how many seats — are actually available on any given flight? Many travelers refer to the seating chart offered by their online travel agency like Expedia, Travelocity or Orbitz. Or you can go to a site like seatguru.com. Or, you can even go to the airline’s own website to see the seating chart. In many cases, the seats showing “available” are only middle seats or seats in the very back of the plane.

But often, all three seating charts are incorrect — or at the very least misleading. Each airline holds back a number of seats on every flight to make them available for their mega frequent fliers and big travel spenders. And if those folks don’t show up, the airline releases those seats on a first-come, first-serve basis.

One of the real challenges, especially for families traveling together, is that the upsell of the airline seats makes it almost impossible to sit families together on flights without charging them for their seats. But now, the U.S. Department of Transportation may be coming to the rescue, alerting airlines of a possible new rule requiring them to seat families together, which may upset the seat upsell scheme altogether. The proposed rule comes after complaints by flyers who felt they were forced to buy seats so their families could sit together.

How can you get the best seats without having to play the upsell game? When you first book a flight — even if you do it online — call the airline directly and talk to a reservations agent and make your seat selection. They’re the only ones who have the only accurate and updated seat availability on their screen.

If you do pay for a premium seat and your flight is delayed, if you’re rebooked or if the flight is canceled, don’t forget — you’re entitled to a refund.