Info. please.
 

Looking at many of my old boarding passes. I know there a number of letter designations that could at the "class" area. I have seen on some sites that an X there would designate !st class ? I never fly first ! and yet an X appears often. can somebody clarify this for me ? Thank you Sam

You're confusing the cabin flown with the booking class. Cabin flown is generally First (F), Business (C or J, depending on the airline), or Economy (Y). In other words, it's the actual cabin you are physically sitting in on the flight.

The booking class is generally airline-specific and an indicator of which type of fare you purchased. An X fare might be a deep discount Economy ticket, while Y and B are generally full-fare Economy. J or C are generally full fare Business, while F is full fare First. Different fare classes within the same cabin flown will have different prices and different restrictions on things like changes, refunds, and advance purchase requirements.

Here's a Wikipedia article and a list of all United Airlines (just to pick one) booking codes.

There are many places on a boarding pass where the X might occur. Perhaps someone could give you a more precise answer if you were more specific about where the X was located and if any numbers or letters were in front or behind it. For example, did it follow the flight number?

Info. please.
 

X is primary bucket used by AA for domestic upgrades. Typically they are the complimentary ones that an EXP receives on domestic flights and I assume non-EXPs using 500 mile certs (never been a non-EXP on AA so don't know for sure).

On UA it is an economy award ticket fare bucket so if you haven't flown first class, that is the most likely place you've seen it.

It's also a heavily discounted economy class on DL so you may have seen it there too.

If it's on your BP it's likely to be from UA or AA as airlines don't typically print the fare bucket on your ticket but in the case of AA and UA those buckets actually are printed bc they represent the fare class (e.g. Y or F) as well