Personal wikis vary but are roughly similar to Wikipedia and related projects, but built (or modified) for individual, desktop or local use. If that interests you, alongside the post link to Feather Wiki, you might also like the following:
More traditional wiki but adjusted for personal, portable use:
DokuWiki on a Stick
Also if these interest you, check out the !pkms@lemmy.blahaj.zone and !journaling@sh.itjust.works communities!
Keeping it simple with files and folders is one of the aspects of Zim that I appreciate. When I take the time to use it it helps prevent me from scattering text files all over the place.