# Creating book content

The two kinds of files that contain course content are:

• Jupyter Notebooks
• Markdown files

Each are contained in the content/ folder and referenced from _data/toc.yml.

If the file is markdown, it will be copied over with front-matter YAML added so that Jekyll can parse it

You may notice that there’s a sidebar to the right (if your screen is wide enough). These are automatically generated from the headers that are present in your page. The sidebar will automatically capture all 2nd and 3rd level section headers. The best way to designate these headers is with # characters at the beginning of a line.

This section is here purely to demonstrate the third-level header of the rendered page in the sidebar!