About using master pages
Master pages contain the design and layout elements that you want to repeat on multiple pages in a publication. Using master pages for these common elements gives your publication a more consistent appearance. It also lets you create and update these elements in one place, rather than changing them on each page where the design elements appear.
A master page can contain anything that you can put on a publication page, as well as some elements (such as headers, footers, and layout guides) that can only be set up on a master page.
Every new publication starts with one master page by default. However, in publications with more than one page, you can create multiple master pages to enable more versatility in your publication design. For example, the first page of a chapter is usually designed without a header or page number, although it may share other design elements, such as margins and layout guides. By creating multiple master pages, you can have a variety of layouts that you can apply to any of the pages in your publication.
You can create a new master page from scratch or duplicate an existing master page, which you can then edit to change just those elements that you want to be different. You can create each master page as either a single- or two-page master. You can also convert a single-page master to a two-page master, or convert a two-page master to a single-page master.