Whenever you create a topic or comment, you’ll have a formatting toolbar that will let you apply most common formatting codes to your text. But what if you want to just type in the formatting?
The main formatting language for Discourse is Markdown, in particular the markdown.it variant. An online demo for that is here:
https://markdown-it.github.io/
Now that’s a bookmark-worthy page right there. 
This is a great idea and post. May be worth on our side to create a simple howto for markdown.
Often times we take for granted our knowledge that we don’t even think about. I have been taking notes in markdown since early highschool!
That’d probably be a good idea. A weak spot of Discourse IMO is that there’s no single place where a lot of these things are documented. “We use markdown.it, look here for how to use it, except we add these codes, and take away those. We support some BBcode; look in the source code to see which codes. We support some HTML, look in the source.”
Of course, one issue is that supported codes can change depending on which plugins you have installed on your instance. But it still seems it shouldn’t be that hard to at least document the defaults in one place–and Discourse doesn’t do that, at least not that I’ve found.
It would be nice if Dan could add the Forum-How-To tag to this as well. (I read elsewhere that wasn’t an option for this post)
On the subject of formatting a post - I didn’t see this mentioned in the link, but one thing I find useful is the spoiler.
[details="Click Me"]
Add your content here
[/details]
Here’s an example of how that looks once it’s posted.
You can hide pictures and code here as well
Here is a code block
I agree. @kris, any idea why that tag could go on this topic: How to use footnotes in this forum but not the others I’ve created in this category?
Fixed. The tags were setup with some restrictions based on category. They should be more generally available now.