A book is a set of pages tied together in a hierarchical sequence, perhaps with chapters, sections, subsections, and so on. The book content type should not be used as a discussion area. It should be used for final product, one-way style communication of information such as manuals, resource guides, FAQs, etc. If you need a discussion area, please use a wiki or discussion forum.
Users who have permission can create a book and write, review, modify, or rearrange the pages. Many users can work together on a book -- you can allow or disallow collaboration, to whatever extent you want.
Go to the create book page.