What is an index?

An index is a roadmap to the information in a document, which can be a book, journal article, Web site, database, technical manual, catalog, graphic image—anything that requires an organized approach to the content.

The index is a guide to the concepts in the document, written from the user’s viewpoint.  The terms used by the author will certainly appear in the index;  but a good index includes additional terms and cross references that the user may be seeking.  For example, in a medical book written for professionals, the author may talk about ‘myocardial infarction’ and ‘cardiovascular accidents’.  If the book is likely to be used by non-professionals, the terms ‘heart attack’ and ‘stroke’ will also appear in the index, since those are the words familiar to a lay person.

If the words sought by the user do not appear in the index either as a term or a cross-reference, access to the information in that document is lost.

What makes a good index?

The American Society for Indexing’s Index Evaluation Checklist can help you judge the quality of an index.  Essentially, a good index

• is appropriate for the intended audience and written from the user’s viewpoint.
• has no more than 5-7 undifferentiated locators (page references) for any main heading or subheading.
• uses see and see also cross references appropriately.
• uses subheadings appropriately.
• avoids unnecessary words and phrases (“concerning”, “related to”).
• uses a consistent and clear format.
• is well-edited, with accurate locators and no typographical errors.

Why hire a professional indexer?

An index is an intellectual collaboration between author and indexer.  The author provides subject matter knowledge, and the indexer contributes professional skills, objectivity, and a fresh viewpoint to the text.  Specifically, the indexer provides

• knowledge of current standards of indexing and information retrieval.
• use of dedicated indexing software permitting easy compliance with virtually any index style guideline.
• delivery of the index in a variety of print or electronic formats, including embedded codes in a text file if required.
• quick turnaround time.

For additional information, see Indexing for Editors and Authors: A Practical Guide to Understanding Indexes, by Fred Leise, Kate Mertes, and Nan Badgett (Information Today, Inc., 2008). The American Society for Indexing’s web site also offers advice for editors and authors about indexing and working with freelance indexers.

ASI's recommendations for Best Professional Practices reflect what you should expect from the client/indexer relationship. The ASI Excellence in Indexing Award (formerly H.W. Wilson Award) recognizes excellence in book indexing with awards to both the indexer and publisher of award-winning works. Samples from award-winning indexes can be viewed on the website.