If I understand it correctly from some followers that I know, "Q" would drop messages on a message board that had messages and "hints" of things that were happening. There was enough there that was correct that made people believe that this person was a high level insider.
It seemed to me at the end, though, that at the end, most of the posts that I saw were "mysterious clues" that could be interpreted 100 different ways and the big conspiracies never seemed to flesh out. So he might just be that boogey man after all.
Q did bring a lot of attention to child sex trafficking though and I am amazed at how big of an industry that is and how many people are involved. I wouldn't have known that this ship was part of a conspiracy theory at all if it wasn't posted here.