System pages get shown to users in certain situations.
Page not found will be presented when a user types in or clicks on a page that does not or no longer exists.
Login Required will be presented when a user who is not logged in tries to access a page that has restricted permissions applied to it.
Access Denied will be presented when a user who is logged in tries to access a page that they do not have access to.
Error will be presented when the CMS encounters an error.
