Primer on how to use text formatting and user tagging here in the community?

There doesn't seem to be any primer on what type of code is needed to format text or tag users. Your \_ring members seem to be tagging and formatting, so there's got to be a way, but what format is used, I don't know. Does it use markdown? Html? It's own special tags? Would be helpful with long topics and helping ensure replies get directed to the correct people by tagging them. Thanks!