Find one of these books with an alphabetical index, and without any further ceremony, remove it verbatim into your own . . . at least, such a flourishing train of attendants will give your book a fashionable air, and recommend it for sale.
—Miguel de Cervantes
What makes a good index?
An index is good when it accurately reflects the content of the book, is logical and easy to navigate, and yields the results that the reader needs.
In order to anticipate what these needs will be, an indexer analyzes a book through multiple lenses. Using synonyms, cross-references, and multiple entry points, an index should weave a logical route among terms, and enhance access to the text. A good index can be compared to a roadmap for a book, offering alternative routes to key themes and concepts.
Why hire a professional indexer?
Authors often plan to create their index using the indexing feature of their word processor. Unfortunately, this method creates a concordance, an unanalyzed list of words, rather than an index. Conceptual information, which is not usually limited to specific terminology, is not captured with this approach. And important connections, through thoughtfully constructed subheads and cross-references, are not created.
Instead of word searching, indexers do a close reading of your book. As they read, they analyze the content for concepts, connections, terminology, and relevance. Lengthy main entries are broken into logical groupings, which become subheads. A good indexer can also judge what not to include, because the information is not “indexable,” e.g., new or substantive. Objective analysis of a text for indexability is hard at the best of times, and particularly challenging when the book is your own.