In addition to Gregory's insight on fare guarantee & seat reservations, I'd like to add some more information.

When you confirm a reservation, receive a record locator number & are told the ticket must be paid for within 24 hours, that seat is actually removed from airline inventory. So if there was one V seat left & you reserved it, the V inventory would be 0. However, inventory management is very complicated & changes constantly.

The 24-hour rule for purchasing an airline ticket holds for many domestic & some international fares. You'll see specials now & again that require ticketing at the moment you make reservations, but that becomes obvious when you get to the last stage of the reservations process.

Fare guarantee for reservations made by phone directly to the airline MOST LIKELY are good for 24 hours. But you must ask if you're not told this information at the time of booking because not all airlines do guarantee the fare. I know, Gregory, that seems like a public relations nightmare at best, but I can't tell you how many times every week I fought with several airlines to protect a quoted fare within the 24-hour period when the fare increased. And, yes, Andrew, it is most likely that the fare changed between your having made the reservation & having actually purchased the ticket.

So, fare guarantees for reservations made with a travel agent will depend on the airline involved & if you're not told about the rules for that particular airline, ask!

For online reservations, whether with the airline directly on its own website, or thru an online agency such as Orbitz, Travelocity or the like, you must very carefully read the fine print on the rules of the fare you're purchasing. For the most part, a credit card number is required to make a firm reservation online; when you plan an itinerary but don't use a credit card to guarantee it, there is no way to lock in the fare. That itinerary is on temporary hold, but there's no guarantee it will be the rate you thot you had unless you purchase at the moment you hold. The seat is temporarily removed from inventory until you decide.

I've never been able to understand why this has become such a difficult process, but airline pricing & ticketing is truly byzantine.

Gail In Eugene