It allows you to create a "wiki"-like website for your own creation - they suggest it for authors, roleplayers, games masters and the like. I took one look at it and immediately realized I could avoid the major problem I have with making using a blog to keep track of fanon stuff; namely, an "encyclopedia" of a fictional setting isn't a diary!
I immediately signed up and started moving content from this blog over there - you will see the gaps, I am sure! The goal is to move everything related to the background, setting, history etc. over there and leave this blog as what it should be - a blog, detailing my hobby progress and so forth.
Check World Anvil out - both the site as a whole, and my own corner of it!
=][= Danforth Laertes