Using the right Markdown ensures that I can type out a code in my HTML posts and prevent WordPress from converting it into HTML.
It has been somewhat difficult using the Markdown function to indicate code blocks in my HTML articles1, as I found that it would sometimes still convert a code into HTML. I discovered after a few trials that it was important not just to cut & paste the code in between the Markdowns but to actually type it out.
Check out https://en.support.wordpress.com/markdown/ to see the Markdown reference lists.
An example of a Markdown:
Crossfade 