What is `server_plugin_outlet`?

I came to know about this thing called server_plugin_outlet. My question is, what is it useful for?

Haven’t seen anything useful about this on meta.

Note: Its not something urgent.

It’s used to add additional html to .erb templates. IIRC it uses a similar connector folder structure as the client plugin outlets. There’ll be a helper in the app folder that’ll tell you exactly how it functions