GitHub combines a syntax for formatting text called GitHub Flavored Markdown with a few unique writing features.
Markdown is an easy-to-read, easy-to-write syntax for formatting plain text.
We've added some custom functionality to create GitHub Flavored Markdown, used to format prose and code across our site.
Text formatting toolbar
Every comment field on GitHub contains a text formatting toolbar, allowing you to format your text without learning Markdown syntax. In addition to Markdown formatting like bold and italic styles and creating headers, links, and lists, the toolbar includes GitHub-specific features such as @mentions, task lists, and links to issues and pull requests.