You should use master pages if you want to use the same elements in the same way on different pages, e.g. the chapter's title in different book pages, a logo in the upper right corner of a catalog,a color area or an image background in a photo album.
All objects which you place on a master page will be shown on each document page automatically. However, you have to firstly assign the relevant master page to the corresponding layout pages for this to happen.
You can use unlimited master pages in a document. So you can assign master page A to the first 20 document pages, assign master page B to the next 20 document pages, etc. Or use a master page with different layers which you switch on and off when producing a catalog with different pages. This way you may create an English and a German version of your sales catalog in minutes.
