Page entity is the central object around which pages are generated. There are three kinds of
Page represents every kind of page
IndexPage is a special kind of
Page that represents a table-of-contents index page
RootPage is a special kind of
IndexPage that represents the very first table-of-contents index page in the book
Page object is passed to every template script. You can use it to find out everything about where the page is in the system, and what the related configuration values are.