What are the master templates?
A Master template is an outermost template that houses your Regions and Content template.
A Master template is an outermost template that houses your Content template. They're commonly used for the websites header, footer and navigation systems. Site Studio allows you to layout your Master template using the Layout builder. You have the option to create multiple Master templates if you want different areas of your website to have different outermost structure.
For more detailed information, see Master templates in the user guide.