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.
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.
You can enable a fixed-width font in every comment field on GitHub. Each character in a fixed-width, or monospace, font occupies the same horizontal space which can make it easier to edit advanced Markdown structures such as tables and code snippets.
In the upper-right corner of any page, click your profile photo, then click Settings.
In the user settings sidebar, click Appearance.
Under "Markdown editor font preference", select Use a fixed-width (monospace) font when editing Markdown.