ok so ive been listening on 40m for a few weeks now and people throw around all these codes and shortened words and i honestly have no idea what half of them mean. like i hear QSL, QRM, QRZ, QTH all the time and i sort of figured out QSL means like... confirmed? and QTH is location maybe? but then sometimes people say 73 at the end of a contact and i dont know if thats a code or just someones number or what. also heard someone say OM and YL during a roundtable and had no clue what was happening. is there like a master list somewhere or do you just pick this up over time. feels like everyone else just knows this stuff already and im missing something obvious

yeah you basically got QSL and QTH right. QSL is acknowledgment/confirmation, QTH is your location. QRM is interference from other stations and QRZ is basically asking who's calling, you'll hear that a lot when someone's running a pileup. 73 is just the traditional sign-off meaning best regards, goes way back to the telegraph days, nothing mysterious about it. OM means old man which sounds rude but its just how hams refer to other male operators, and YL is young lady which is used for any female operator regardless of age. theres a ton more — QRN is static/atmospheric noise, QSB is signal fading, QRP means low power operation. honestly the Q codes came from international telegraphy so that operators speaking different languages could communicate, thats why they all start with Q. ARRL has a full list on their website somewhere, worth bookmarking. you'll absorb most of the common ones pretty fast just from listening

73 tripped me up too when I first started lol. I thought someone was signing off with their age or something. One thing that helped me was just keeping a notepad next to the radio and writing down anything I didn't recognize, then looking it up after. After maybe a month of that I stopped needing to look things up as much. Also dont worry too much about the obscure ones, honestly in day to day operating you only really hear maybe a dozen Q codes regularly. The rest you'd only see on like CW or digital modes where people are abbreviating everything to save time.