Whats This “Gen” or “Generation” BS?!

I know the lingo has been around for a while, really became aware of it by how people were referring to the Cummins powered D-Series and W-Series......there I go again using proper old school nomenclature! Now everything is 1st Gen, 2nd Gen Ram blah blah blah:rolleyes: I got a 90 W-Series, a W-150 Power Ram with a 318 No need for new nomenclature thank you very much. I know what I got:lol:
When you need a fender for a 1990 Cummins w250, and want to know what other years will fit, the term First Gen helps a lot.:)