Markdown styles text to make it easier to present lists, images, code, and other content in GitHub gists and comments within issues and pull requests.Markdown can also be used in popular workplace messaging platforms like Slack!
Markdown can style text to LOOK like code but only for comments.
Since the README file is usually the first thing people see in your GitHub repository, it should give a clear and concise introduction to your project as a whole rather than a detailed summary of every file.

The Markdown Flavors

Because the core Markdown language supports only a subset of HTML features, many independent developers have extended the Markdown syntax to incorporate more HTML compatibilities and customize it for their own organizations. Here are a few popular flavors of Markdown:

[CommonMark]{https://commonmark.org/} is a body of special-interest developers who work side-by-side on a proposal to standardize the Markdown syntax and offer extensive test suites to validate Markdown implementations against this specification. This standard has been used by other developers to base their code upon.
GitHub Flavored Markup, or GFM is GitHub’s expanded dialect of Markdown based on CommonMark and is used throughout the GitHub platform by its active community.
Trello, a popular collaborative tool that organizes and tracks information through virtual boards and cards, implements a custom version of Markdown as well.