Definition of Appendix in a Book or Written Work

Do You Need a List of Supplementary Materials?

The Appendix page of an antique book.
TokenPhoto/Getty Images

The word appendix comes from the Latin "appendere," meaning "hang upon." An appendix is a collection of supplementary materials, usually appearing at the end of a report, academic paper, proposal (such as a bid or a grant), or book. It typically includes data and supporting documents the writer has used to develop the written work.

Examples of Supporting Materials

Not every report, proposal, or book requires an appendix. Including one, however, allows a writer to point to additional information that may be relevant to readers but would be out of place in the main body of the text. An appendix can give the reader more depth regarding the topic, supply resources for further reading or contact lists, or provide documentation to make the case for a grant or bid proposal. That said, an appendix should not be treated as an opportunity for padding.

Appendix information may include tables, figures, charts, letters, memos, detailed technical specs, maps, drawings, diagrams, photos, or other materials. In the case of research papers, supporting materials may include surveys, questionnaires, or schematics and the like that were used to produce the results included in the paper.

Supplemental vs. Elemental

Because of its supplementary nature, it's important that material in an appendix not be left to speak for itself. "This means that you must not put vital information only in an appendix without any indication in the main text that it is there," notes Eamon Fulcher, author of "A Guide to Coursework in Psychology."

An appendix is an ideal place to include information and other data that are simply too long or detailed to incorporate into the main body text. If these materials were used in the work's development, readers may want to reference them to double-check or locate additional information. Including the materials in an appendix is often the most organized way to make them available.

The appendix material should be streamlined, relevant to your topic or thesis, and useful to the reader—but it's not a place to put all of your research materials. The citations in the references, bibliography, works cited, or endnotes will take care of citing your sources. An appendix is a place for items that help the reader's understanding of your work and research and the topic at hand. If the material is not important enough to refer to in your text, then don't include it in an appendix.

Fast Facts: Should You Include an Appendix?

Whether you include an appendix depends on your topic and what will benefit the reader. If you answer yes to one or more of these questions, create an appendix.

  • Will supplemental materials aid the reader's understanding of your topic?
  • Will they provide resources for further reading or exploration?
  • Will they supply additional depth to the data presented in your report, article, book, or proposal?
  • Will the materials provide additional backup for your thesis or message?
  • Do you have items that would be unwieldy to present in a footnote?

Formatting an Appendix

The way in which you format your appendix depends on the style guide you have chosen to follow for your work. In general, each item referred to in your text (table, figure, chart, or other information) should be included as its own appendix. However, if there are many data sets under one grouping, keep them together in their appendix and label each piece appropriately.

If you have more than one appendix, label the appendices "Appendix A," "Appendix B," an so forth, so that you can easily cite them in the body of the report, and start each on a separate page. For the ease of the readers, put your appendices in the order that you refer to them in the paper and don't forget to note them in the table of contents—if your work has one.

Research papers, including academic and medical studies, usually follow APA style guidelines for the formatting of appendices. They can also follow the Chicago Manual of Style. For each of these styles, format the appendix as follows:

  • APA: Center the title, and use upper and lowercase letters. The text of the appendix should be flush left, and you should indent your paragraphs.
  • Chicago: The Chicago style manual also allows for numbered appendices (1, 2, 3, not just A, B, C). As far as location, they appear before any endnotes sections so that any information in the appendices that needs a note can refer to the notes section. If there are many tables in the appendices, though, it might be best to keep the notes with the tables.

Appendix vs. Addendum

An addendum is new material added to a book or other written work after its first edition has been produced. For example, an addendum may contain updated research or additional sources that came to light or further explanation about the book from the author.

Addendums can also be used in legal documents. An addendum can change the terms of a contract, such as canceling sections or updating terms or pricing in sections of a contract without the contract becoming null and void in its entirety, which would require all parties involved to read, agree to, and sign it again. The parties to the contract simply need to sign the addendum, and usually initial the noted changes.