[reshlo]

It’s not just “extended” flavours of Markdown that allow embedding HTML. The original reference implementation supports this too.[0]

> For any markup that is not covered by Markdown’s syntax, you simply use HTML itself. There’s no need to preface it or delimit it to indicate that you’re switching from Markdown to HTML; you just use the tags.

[0] https://daringfireball.net/projects/markdown/syntax#html

[xigoi]

However, there is no way to switch back to Markdown inside HTML, so if, say, you want to have an <article> tag around your article, you need to write it entirely in HTML.