What is Back Matter in a Book?

Back matter is all that stuff that comes AFTER you’ve finished the main content of your book. The elements in the back matter can provide additional information, resources, and, most important for indy authors, marketing space.

The most common components of back matter in books

Endnotes (or just Notes): Sometimes it’s a pain in the butt to note the source of information on the page itself. Many authors put all the notes into the back matter of their books. Some organize by chapter and page number, some just by chapter. This not only verifies that you have properly sourced your information and credited those sources, but it allows your reader to dig more deeply into a topic if they so desire.
Appendix: This can include supplementary material for data that is described in the book such as tables, graphs, or other data. I occasionally put worksheets for various exercises or checklists in the Appendix.
Bibliography or References: If you’re not using Endnotes, you might want to add a bibliography—a list of the books, articles, and any other sources you used to develop the content of your book.
Index: Indexing takes a very special, very patient person. An index is an alphabetical list of just about everything referenced in your book: names of people, topics, terms and concepts, etc., along with the page number(s) they can be found on.
Glossary: If you’re writing a technical book with terms that may be unknown to a large part of your audience, then include a glossary of those terms. It doesn’t have to be extensive, but it sure could be helpful! And yes, it’s arranged alphabetically.
Acknowledgements: The dedication goes in the front, the acknowledgements in the back. Who helped you with your book? You will usually find the names of the agent, any research assistants, editors, beta readers, mentors or coaches, and anyone else who contributed to the project.
Permissions: If you included copyrighted material in your book, you should have a section that acknowledges the copyright holders that granted the permission(s).
Other Books by the Author:If you have written other books, do have a page in the back that lets people know about them. You can give a brief summary of each book. Many authors will say where the books are available and/or they may have contact information for bulk purchases. (Many times bulk purchase contact information is in the front matter on the copyright page. No harm in having it twice.) On an eBook, you can create links to your other books but be aware that Amazon will not allow you to link outside of Amazon. (They’re not stupid.)
Recommended Reading: I write business books and there are some books that I LOVE to recommend; I just think they are important reading for anyone who is interested in that topic. You probably have some favorite books in your field, that you like to recommend, too. Go for it!
About the Author: This is a short bio of you (and any co-authors). It is usually written in the third person. It is a very good place to put what you do, i.e., you are a business consultant, speaker, trainer, etc. I also like to put some contact information on that page, usually my website URL and business email. I do not put my phone number there but if you have a business address and phone number, you may want to.

Is there a particular order to back matter?

As a matter of fact, yes. You don’t have to follow this to the letter and most books will not have all of these elements anyways, but here’s a good order: