About Indexing (from the American Society for Indexing)

An index is much more than an alphabetical list of topics with page numbers attached.

A good index is a road map that leads both experts and novices in your field to every pertinent sentence you've written, regardless of their point of departure and without dead ends or annoying detours. 

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_An index is a tool that helps users locate information.  Users of indexes include:

• Potential buyers and bookstore browsers, when deciding whether to buy your book;
• Librarians and educators, when deciding whether to acquire or adopt your book;
• Book reviewers, when deciding whether to recommend your book;
• Your peers, when judging your book's completeness.

_Creating a good index takes understanding of the reader as well as the subject.

• The index is meant for the reader, often a non-expert, who may not be as familiar as you with the concepts, thrust or vocabulary of the topic.
• A professional indexer will look at your book from the reader's perspective, using synonyms, main headings and subheadings, double-postings, and cross-references to guide the reader efficiently back into the book.