What are some alternatives?
Fandom - Anyone can create a wiki!
DokuWiki - dokuwiki [DokuWiki]
Miraheze - Miraheze is a wiki farm (hosts wikis) for free and with no ads, it also provides custom domains...
Nuclino - Nuclino is a unified real-time workspace for teams that brings all your notes, tasks, and docs together in one place.
Wikipedia - Wikipedia is a free online encyclopedia, created and edited by volunteers around the world and hosted by the Wikimedia Foundation.
Confluence - Confluence is content collaboration software that changes how modern teams work