A template is a predesigned set of elements for creating a book—sample chapters, various page layouts, and so on.
When you create a book in iBooks Author, you choose a template from the Template Chooser. There are 3 types of templates:
Landscape templates are best for books that present a lot of information at a glance, using graphics, media, and interactive features.
Portrait templates are especially good for books with composed pages—for example, newsletters, journals, and catalogs. They’re always in paginated view.
EPUB templates are designed for novels, mysteries, and other books with lots of text.
Although you can modify individual book pages however you like, you can’t switch a book to a different template after you begin creating your book.