A class F ticket C ticket?????? Why does it exist where do you learn it?
Isnt there just First Class/Buss Class/Coach

Then yes you can further break it down window seat, aisle seat, middle seat. Or Coach +, Economy Comfort (whatever depends on the airline what they call it).

Why the letters?

Why different airlines use DIFFERENT letters is a Corporate thing. Sort of like Tall, Grande, and Vente standing in for Regular, Medium and Large at Starbucks.
But.... actually in each of those cabins there's maybe half a dozen fare classes. Those are denoted by letters. Read along on FT for a while and you'll learn just how different J is from Z, though both are Business Class.
It would be nice if fare class designators were standardized across airlines, but that would be a complete anomaly in the world of airline pricing.

I think you're looking for this?
http://www.flyertalk.com/forum/16909-post3.html

It is just "insider lingo." Because the airlines use single letter computer codes to identify different classes, it makes knowledgeable customers feel like insiders to use them as well. It can also be argued that using the correct codes represents precision over using general terms.

You might be interested to know that there are not simply one first class, one business class and one economy class codes. There are codes for fully refundable seats in each class, different codes for partially refundable, non-refundable, deeply discounted and so on. That is where all the different codes come from.

Also final destination means the ticketed airport that is not a connection.
In real life, final destination means the cemetery.

As to the why of the codes: are you old enough to remember multi copy paper tickets? The kind that had to come out of a special printer, and you'd tear out a coupon for each flight leg?

They had to cram a whole lot information on a form about 3" by 7" and putting a single code letter in a box made more sense than typing out "coach class", "14 day advance purchase fare" and whatever other details were needed for their system. Once you learn the codes it's easy to read the ticketing info. There's lots of resources here on FT to help you learn the codes.

A friend of mine learnt about the different fare classes the hard way. I kept telling him to book NOW for a trip to Disneyland for 4 people in September. Of course he didn't. He kept telling me about their Virgin tickets for AUD$1200. When he looked at them late July the only seats available were AUD$1700.

Let's be honest. At least 75%* of the airline/fare/airport code usage in FT posts is because people want to show off that they're in the in-group that knows about this kind of thing.

It makes a certain amount of sense to write "UA" because it's shorter than "United Airlines" and is fairly easy to understand. "DL" for "Delta" doesn't save much typing, though, and "B6" for "JetBlue" is totally inscrutable for the uninitiated**.

It can be absurd with city codes, though. Some people ask, for example, "What is there to do in LAX?" People reply, some of them suggesting the poster watch airplanes and others saying "Not much." The poster really wanted to know what there is to do in Los Angeles, but had to show off that he**** knows the code for its main airport.

_______________________
*Or not. Pick a number. The point is the same.
** Canada's Helijet International already had the JB code when JetBlue began. Don't ask me why. Nobody has HI today. Maybe someone did back in the day.
***Los Angeles International Airport.
****Or she, but usually he.

This. Data space used to be critical and the codes are designed for that era.

People abbreviate all sorts of things and it falls into everyday use. Fridge, car, TV, phone, bra, plane and so on. It's human nature to save ourselves effort, even if the increment is minuscule.

To seem cool, obviously.

That may be so, but it's also easier to type.

qft

This is why for a decade people used to SAY "double you double you double you" instead of "World Wide Web." Because it's three times as long😏

Lol