An index is the reader’s key to the text’s context. When written well, a good index provides immediate access to–and understanding of–the meaning of the text.
The reader should, with confidence, be able to discern what’s covered in the text and what’s not by using the index.
The Chicago Manual of Style (16th edition) explained that a good index “gathers all the key terms and subjects (grouping many of the former under the conceptual and thematic umbrella of the latter), sorts them alphabetically, provides cross-references to and from related terms, and includes specific page numbers or other locators.”
In other words, an index is more than an alphabetical list of all locations of the keywords in the text.
To create a good index, the indexer must balance these two components:
- Inter-related structure. Like a map, an index allows the reader to quickly find ideas, concepts, and terms on demand. Features of this multi-dimensional map include alphabetization, headings, and subheadings to pinpoint the exact reference the reader needs, and cross-references to provide cross-structure.
- Analysis. Imposed on the structure, the indexer breaks down and rearranges the author’s information into a convenient, easy-to-access document.
Why add an index?
- Indexes add value to your nonfiction book by directing readers to key ideas through multiple access points.
- A good index will provide a convenient representation of your book’s concepts.
- Potential buyers will evaluate your book’s index before making a purchase.
- Researchers will have difficulty using a book without an index.
- Librarians are reluctant to buy nonfiction books without one.