The Tildes Wiki
Note: This feature is currently being experimented with, and is available to users who message @Deimos
Wikis are useful for common databases of information, rules and traditions that a community might have. Unlike comments, all content in the wikis are shared under the Creative Commons Attribution-ShareAlike 4.0 license and they have a git history available publicly (so do not post personal data because it can't be deleted!).
Currently there are quirks with the system which should be fixed in the future :
Groups with no wikis have to be manually navigated to to create pages in them such as https://tildes.net/~tildes.official/wiki, if you have permissions, you'll have access to a button to create new pages.
Pages can't be renamed or deleted, you'll need to message Deimos for that.
Permissions are global, there is no permission system per-group.
Reference: A basic wiki system is now available for groups