An excerpt from http://www.sitepoint.com/the-best-markdown-plugins-for-wordpress/, by @elioqoshi
With more and more information floating around the interwebs, it has become a quite challenging task to keep your head cool. Content creators are often limited by the software or formats they’re using, effectively locking them into a silo ecosystem (looking at you Google Docs and Evernote!). With this in mind, John Gruber created the famous Markdown format in 2004. Today, it empowers writers and bloggers with the ability to write in HTML, without the use of overcomplicated and visually exhausting code.
Yes, basically my grandma would be able to read Markdown without giving me a confused look. Its extended portability and precision, coupled with its simplistic implementation, make it one of the few tools one simply needs to love.
Further, Markdown is the de facto syntax language for GitHub and Stack Overflow, two sites where most web developers spend most of their time.
As Markdown combines the best things from two worlds, it’s also greatly accessible in WordPress, allowing you to have more power over your content than with the WYSIWYG (What You See Is What You Get) editor.
In this article we’ll cover four of the best Markdown plugins for WordPress.