Markdown is a text-to-HTML conversion tool and it can be used on the GitHub platform. It will control the display of the text on the pages by converting the plain text formatting to HTML. You don't need to edit the css file to change the attribute of your text. To control the transform, you need to use some non-alphabetic characters thrown in, like # or *. Markdown will help you transform the plain text to bold , italic, adding links or images. Markdown is not only available on GitHub.com. You can download it from daringfireball; however, Markdown also requires the standard Perl library module. ##Source: https://guides.github.com/features/mastering-markdown/

http://daringfireball.net/projects/markdown/