Markdown markup language
is a markup language with plain text formatting syntax designed so that it can be converted to HTML and many other formats using a tool by the same name. Markdown is often used to format readme files, for writing messages in online discussion forums, and to create rich text using a plain text editor.
Markdown is a lightweight and easy-to-use syntax for styling all forms of writing on the GitHub platform.
Markdown Basics allows you to write using an easy-to-read, easy-to-write plain text format, which then converts to valid HTML for viewing on GitHub.
You can check Markdown Cheatsheet and Github Flavored Markdown as well.
You can also read Mastering Markdown for 3 minute read from here.
If you’re using Macintosh, another easy way to edit and view Markdown text formatting syntax is to use ideally LightPaper for Mac.
LightPaper – is a simple, beautiful, powerful, yet free text editor for passionate writers. You can use LightPaper to write any kind of text documents — blogs, articles, notes, READMEs, TODOs, or the next chapter of your new novel. Its simple interface gets out of your way, allowing you to focus on writing. To remove distractions, you can switch to Distraction-Free Mode to completely immerse yourself in your current paragraph. It comes bundled with a handful of themes and beautiful fonts. You can also easily create your own themes or add existing ones.