At a high level, all sites have major regions. These include the header, a secondary menu, main content area, and footer.
The header region contains the site logo, utility and main menus, and search tool.
Depending on your site's theme and menu configuration, there may also be a secondary/tertiary region that appears as a left sidebar. This will contain parts of your primary or utility menus.
The content region is where information from your content items is displayed. It's also the area that you can control using the layout tool available on the Page content type to build landing pages.
The footer region contains the footer content such as the Princeton University logo, copyright information, general contact information, social links, footer menu links, and accessibility link. The footer also has a customizable area where custom content can be placed.