Blank pages in a book should be completely blank. That means no page numbers and no running heads! Blank pages often appear on the left hand side before a new chapter or section in a book.
Section breaks are used in Microsoft Word to correctly control needed blank pages (as well as chapters, page numbers, and running heads). A Section Break: Next Page will tell Microsoft Word to start the next section (chapter) on the next page in a book. A Section Break: Odd Page tells Word to start the next section on the next right hand page in the book. If needed, Word will automatically insert a completely blank left hand page to make sure the next section starts on a right hand side. This often confuses people as Word will not show you that blank page until you print or create a PDF and it makes it appear that Word skipped a page or that it is not starting the chapter on a right hand side, when it actually is.
Hint: odd numbered pages are always right hand pages.
The Book Design Wizard will automatically setup the section breaks for you in your book.