This is the original main thread. It's about the last release that has made it to the Play store. It also lists the complete changelogs, including those of the beta releases. If you don't know where to post your comment or question, this is usually the place.
This thread is meant specifically for discussion of the latest beta release. These may or may not be newer than the latest stable release. Sometimes there is active beta development, sometimes new things go directly to stable, and sometimes it's just quiet development wise for both versions.
This thread is mean specifically for discussion regarding SuperSU for developers. This goes much deeper technically than the STABLE and BETA threads, and is meant to separate the important developer stuff from the more user-focused threads.
This thread is meant specifically for discussion regarding my How-To SU guide, aimed at developers. See the thread for further information.
Additional threads - bug reports, feature requests, etc
It is certainly not needed to create a separate thread for every little thing. However, please do check if a thread regarding your question, comment, bug report, or feature request already exists before posting anything.
If you are reporting something about the beta version, please check if the issue exists on the latest stable version. If it does, the post should go to the stable thread, not to the beta thread.
There is no strict set of rules about whether you should start a new thread or post to the main threads. Use your best judgement. If an issue seems persistent across a number of SuperSU versions without getting solved, it affects a large number of users, or generates a lot of discussion, then maybe it does deserve its own thread.
If you have posted a new thread, please report that fact to either the stable or beta threads, so both myself and other active users can monitor just these two threads instead of the entire subforum.
When you post something, either to a new thread or an existing one, please include as much information as possible. Such as which version you are talking about (latest is not a version number), if you have tested other versions, what your setup is - device and exact firmware information welcome -, exact reproduction steps explained as if the readers are five years old, etc. Help us help you.