Discourse supports Markdown in posts. For those unfamiliar with Markdown , which has become very much of a standard, here is the syntax from the inventor. You can learn it in a few minutes. It’s supposed to be easy.
Markdown has a design outlook that is that it should be easy to understand in programs that can’t render the generated HTML, such as text only email programs. You get used to reading it very quickly. It came from the old of idea is using *stars* like that to emphasize plain ASCII text.
Mail programs like Thunderbird render Markdown in email nicely. So Discourse provides a good rich editing environment, a cut above plain text, if you so desire.
This is italics and this is emphasis.
This is also a good site with a cheat sheet: