Yoshihiro Togashi's Hunter × Hunter is one of the most enduringly popular manga series ever to hit shelves. Launching in the pages of Shonen Jump in 1998, the story has captured fans' imaginations and left them desperate for more. Because of this, the manga has spawned several adaptations, including anime, stage plays, and drama CDs. One reason for this popularity is the story's fascinating and in-depth world-building. This is best seen with the Hunter Association, as its rank system helps make the world feel much more alive.
Source:https://www.cbr.com/hunter-association-rank-guide/