Package blackfriday is a markdown processor. It translates plain text with simple formatting rules into an AST, which can then be further processed to HTML (provided by Blackfriday itself) or other formats (provided by the community). The simplest way to invoke Blackfriday is to call the Run function. It will take a text input and produce a text output in HTML (or other format). A slightly more sophisticated way to use Blackfriday is to create a Markdown processor and to call Parse, which returns a syntax tree for the input document. You can leverage Blackfriday's parsing for content extraction from markdown documents. You can assign a custom renderer and set various options to the Markdown processor. If you're interested in calling Blackfriday from command line, see https://github.com/russross/blackfriday-tool.