Newbie here. There's a lot of great information in different forums and I am still trying to get a handle of it. One thing that I am quite confused with is the airfare classes as I've seen that mentioned in a lot of MR deals and whatnot. I looked it up and found this:

http://en.wikipedia.org/wiki/Travel_class#Fare_class

But what is the difference between the different economy classes? I read in a couple of threads in the MR deal forums that they'd want G or K class while some don't seem to be very high on L. What does that really mean in terms of those classes? And how do you book specific class in, say, united, or whatever airline's website?

Thanks ahead

Welcome to FT!

Differences among fare classes for a given cabin include:

1. Obviously, the fare.
2. Terms and conditions: advance purchase, refundability.
3. Frequent flyer credit earned.
4. Upgradeability: free if seats available, inexpensive, expensive, not allowed.

There is little or no standardization among airlines in these respects, except for two things:

1. A few codes, such as Y for the most expensive economy fare with the fewest restrictions.
2. When a given fare is sold out, all lower fares are also sold out. This is called "fare bucket nesting."

If people post that a given fare class is desirable, that generally means it earns more frequent flyer credit than others at a reasonable price. If posters try to avoid one, that's usually because it earns little or no such credit.

Many mileage runners are concerned with earning FF credit, especially to reach status levels in an airline's program. The details of how fare classes relate to that vary widely from airline to airline and can be complicated. It is impossible to recap them all here. Things get even more complicated when you factor in issues of earning credit in one program while flying with an alliance member or other partner airline. Check the forum(s) of the airline(s) you're interested in. The information may already be in a "sticky" near the top of the forum. If not, try searching. This information is also usually on the airline's Web site, but can be hard to interpret there.

Booking a specific fare class on an airline's Web site, or on a general travel site such as Expedia or Orbitz, can be a challenge. Many of them let you choose between, say, "refundable economy" and "non-refundable economy." Most let you find out what fare class a ticket will be in but don't let you do much about it if you don't like what you see. You must often speak with an agent to find out how much more expensive a more desirable fare class would be and, if the difference is small enough, to rebook a flight into it.

Thanks a lot Efrem! I was hoping to hear that the classes would have some sort of chronological order to make things easier (e.g. G>K>L>M>etc etc). I guess it didn't work that way.

Still, that clears up a lot. I definitely have a lot to look up. Many thanks again!

I need some help on this subject as well. I have a restricted economy W on BMI. The ticket was booked with a travel agency for me as part of a business trip. I have no access to the agency. I'd like to know the fare rules. Can I find them here on flyertalk? Also is there someone with access to the site that lets you see the number of seats available in each class? I had access to it, but it expired, as I only use it occasionally. I'd like to see the status of the seats on one of my flights. If anyone can help, it's BMI flight 4861 LHR-YHZ, either June 28 or 29. Thanks so much.

For the large airline forums within FlyerTalk, there may be a wiki or FAQ within each airline forum that lists each airline's sequence of fare classes. This thread from our United forum is a complete discussion of booking classes on UA; but, as noted, each carrier uses its own codes and order.