.md file

Whenever you create a new article (sometimes called a chapter) in GitBook, it gets placed in a file by that name, ending with .md. Ultimately, GitBook will create an HTML file by that name. For example, if you create a chapter named Keyboard Shortcuts, GitBook puts it in a source file called keyboard-shortcuts.md. When it gets published, it will generate a file named keyboard-shortcuts.html. The more specific and useful these names are, the more easily they can be found through web searches.