Signal Wiki is an unofficial wiki about the (open source, non-profit) Signal messaging app, describing its features (both from user-facing and internal perspectives; whether they're released or in development), changes and updates, intricacies, terminology, development process, and other information related to Signal.
It's about the app, its components, forks (modifications) of these, and related official or unofficial projects.
It can go more in-depth than the official support articles, for example help people understand more precisely what certain options do and in which cases they should be used.
A lot of this information is already available, but is scattered across forum posts, tweets, source code comments, etc. The goal of this wiki is to organize this information and build upon it, for example in the form of guides.