Hierarchy
Templates can be created to form a certain hierarchy. This helps in creating applications that have elements that return in exactly the same form on several pages. Most applications are built with a certain hierarchy in mind. For example every page contains the same toolbar and the same sidenavigation, while certain “sections” might contain the same elements as well.
The descendants will inherit all settings & elements that are on the ancestor/parent pages. This allows you to create a root template containing for example a sidenav & a toolbar which will automatically be displayed & kept in sync on underlying children/descendants of that root page.
You can have as many nodes and levels in your tree as you want.
You can have as many trees inside an application as you want.