There is basically three (somewhat overlapping) lists of Q-codes used in Ham Radio. The three lists are those used by voice operators (SSB), those used by CW operators, and those used in CW traffic handling nets (QN codes).
A full single "official" list of Q-codes is not useful to the ham radio operator. What is useful is to know those that are commonly used. The use of Q-codes is most dominant among CW operators because CW begs the use of abbreviations to limit keying. Use of Q-codes among voice operators, mostly SSB is also common but the usage is typically more limited to just a handful such as: QSL, QSO, QSB, QRM, QRN, QTH, QSY, QRZ, QRL, QRU, and maybe a few others I am missing. But, many times a voice operator will merely say something equivalent to the Q-code meaning. For example, he/she might say "I am being interfered with" instead of "there is QRM" or "there seems to be a slow fade on your signal" rather than saying "some QSB on your signal". Note that I am listing these as I think of them and obviously the same set is not the common usage of all operators. But, you can expect to hear these at times among SSB operators. [By the way, many SSB voice operators would say "QR-Mary instead of QRM or QR-Nancy instead of QRN (atmospherics noise or other non-operator RFI)].
With CW operators, you can add to the list signals (above) such as QRT, QRV, QSP, QRS (and, less frequently QRQ), QST (by scheduled nets usually).
And, within a CW traffic net, the QN signals are common such as: QNI, QNX, QNZ, QNA, QNZ, QND, and a few others.
When asking a question via a Q-code in CW it is common practice to include a ?-mark following the Q-code. For example, a CW operator will check to see if his frequency is clear by sending QRL? meaning "is the frequency busy?". An answer of the letter C from someone if the answer is yes, it is busy. The letter C is a common CW abbreviation meaning Yes.
Now, in the above lists I did not define these Q-codes because they are very easy to look up. The ARRL has lists published on their web site plus these Q codes and many more are published on many web sites. Just Google "Q signals ham radio" or some variation of that and you will find them.
Also above, I did not list every Q-code known to amateur radio. Some are never heard. I am almost 100 percent CW activity and I spend a lot of time on CW traffic nets and I use maybe a dozen total Q codes from the regular Q code lists and the QN codes.
A. List of Abbreviations in Alphabetical Orderin theITU Radio Regulationsone gets the impression that about half of the abbreviations are not useful for amateur radio. Take the first three for example:QOA,QOB,QOCare about telegraphy on frequencies outside the frequencies for amateur radio. $\endgroup$