A good index provides readers easy access to the subjects of importance found in a book. Not by alphabetizing strictly words from the text (known as a concordance) but by presenting a reorganization of the ideas found in it. This reorganized structure includes not only the text's terminology, but also alternative terminology that addresses both potential readers' point of view and the need for concise expression of those ideas.

Professional indexers use techniques to bring the author's ideas together with the reader's mind, by culling important information from the text, reorganizing it in useful ways, and using cross-references to increase accessibility.

Publishers, Editors and Authors:
for more on indexing and working with indexers, see the website of the American Society for Indexing at www.asindexing.org/site/editorsguide.shtml