How Dose Wynncraft Store Information About The Players?

I'm trying to research the feasibility of making quests and NPC interactions more dynamic. Making changes on the scale I imagine would probably require keeping track of a lot more information about every individual player. Wynncraft already dose something to remember data about the players' quests, discoveries, skills, etc. for all the players' characters. What system are you using now and what are the limits to how much info this system can store?

(I know basically nothing about how Wynncraft or minecraft servers in general operate, so please explain any jargon you happen to use.)