I really love the Org-mode markup language. It allows me to compose just about any document that I would actually want to write. That means that I can typeset bold, italics, underline, monofont, and even strikethrough. But some people have more imagination or are just weirder and want more ways of emphasizing text.
What additional ways would you want? The Emacs Notes blog has an answer. I can’t imagine myself ever wanting to typeset something like that example but as the post makes clear, the method is pretty general and allows you to specify emphasis markers that will use whatever font you like, in whatever color, weight, and size you desire.
The TL;DR is that you just need to load org-extra-emphasis.el and configure what you want the extra markers to produce. The blog post covers this in detail so take a look if you’re interested in this capability.
As I said, it’s highly unlikely I’d ever need this facility but it serves as a wonderful example of the extreme extensibility—or perhaps meta-extensibility in this case—of Emacs. In any event, if you need a bit more markup for Org mode, take a look at this post to see how to get it.