The page is an object as any other
All the objects can be moved within or across the pages
It is easy to understand that pages can be moved around, too. This is one of the most powerful use cases of a layout program. Let's say you've added the pages for London at Pages 5 and 6. But you later decide that your magazine will be some kind of trip metaphor and you want to show each step of it by beginning from London. In this case, London will become the first city in your document and should be placed before the pages for Brussels.
More generally, in professional magazines, a user is mostly used to managing advertising pages. Suppose a client pays for a full page near the page for London, because he has a market there and finally decides that the last page would be a better fit. And shortly before pressing the print button (for thousands of copies) you need to change it.
You will again have two ways to make the change:
To move the pages one by one, go to the...