I had such a book to index a few weeks ago.The subject was the music industry. The following list includes 10 of the approximately 175 such terms needing a gloss for this book:

A&R (artist and repertoire); Boom Bip (artist); CD Baby (online music store); Central Park (New York, NY); Domino (record label); Ghostface Killah (artist);  Interscope (record label;  Lang Lang (artist); Nielsen Soundscan (research organization); Sam Goody (music store); Ted Leo and the Pharmacists (band).

Although-time consuming, the research and added reading needed to add these glosses was a learning experience in itself.

In the preface the indexer stated that buyers “will have in the back of the little book a most extensive alphabetical index which has been completed with great care…and they will benefit mightily from the many labors I have bestowed on it during a long time.” Among the entries are the following:

Good will of listeners, gaining of

Study of the art of preaching, not to be neglected

The church history and theological books I write indexes for often cite or refer to Augustine.

Rose Ippolito, an indexer, offered to index his book Thirty Percent Chance, and he accepted the offer. He commented that “in doing so, she paid scrupulous attention to the book, not only to every fact and proper noun but to every nuance and idea inhabiting the shady nooks and crannies of the book’s intellectual woodland. It was the kind of attention that makes any author roll over and lie on his back, purring, as if having his belly fur scratched.”

He said he went back to Rose’s work, and was struck by how the very act of creating categories of thought produces interesting and pregnant juxtapositions. Under “rain,” for example, she gives us:
almanac predictions
animal sense of smell
colored
first rains of the season
flooding, causing
fondness for
harvesting
as holy
rainmaking attempts
rain worshippers
sickness, causing
trees, affecting
umbrellas
in Vermont
video
words for

He wonders if those index entries not be some kind of skeletal poem, and have a kind of coherence that underlies the entire text even if it may never be articulated or even recognized by the author.

You can read more in the November 9, 2011 posting of Publishing in the 21st Century: The Blog.

Human indexing does not perform the same operation as automatic indexing. It is a process of intellectual analysis of the meaning of a book, with the aim of re-arranging its concepts in a searchable format. It results in the construction of a parallel but differently organized text. Multilevel headings, cross-references, and double-postings are part of the index.

Automatic indexing aims to find words used by the reader to match them with the same words occurring in the book. It does not offer the searcher synonyms for the terms used in a text, or display relationships among concepts
Multilevel headings, cross-references, and double postings cannot be found.

Automatic indexing cannot indicate concepts that are implied, or distinguish between minor or minor topics. It does not take into account the variety and complexity of human language that make ideas meaningful to a reader.

A large number of searches in an automatically indexed database will be of the”quick and dirty” type, missing all relevant ideas whose terms happen to be different from those of the reader.

When automatic indexing is used it will be misused. It fails every important quality test.

Single indexes are preferred for most books. Their advantage is that readers need to look in one place only, and don’t run the risk of missing an entry because they were looking in the wrong index.

Books on scientific subjects, law, theology, and classical literature often need multiple indexes.

Matters can be taken too far. For example, translators for a 16th century pharmaceutical book announced that it would have “a Chinese Index, a Japanese index, a set of indexes for the other Asian languages, a clinical index, a General index, and an index of botanical synonyms.”

A book on theology I indexed recently needed an Index of Subjects, an Index of Scripture, an Index of Ancient Sources, and an Index of Greek Words.

Although not always the case, a book with multiple indexes could be more useful for the needs of the reader.

Not every book needs an index. If the information in the book is ephemeral, likely to never need retrieval by a reader, you might not need one. If it will not be judged quickly by browsers who are looking for an index, you might not need one. Most fiction books do not need one.
Otherwise, it could be pretty useful. If you wrote a book you want people to use for reference, an index adds value and avoids frustration. Many bookstore browsers look first in the index to see if the book answers questions or addresses issues important to them. Librarians will eliminate a lot of books they consider simply because they lack an index. You take a big chance of having lower sales of your book because it doesn’t have an index.

“Without a key we search and search in vain,
but a good index is a monstrous gain.”
- Anonymous

Let’s say you decide your book does need an index. You decide to not write the index yourself, since you don’t want to. Shopping it out to a relative or a grad student does not seem to be the best solution since you definitely want a good index.
What can you do to improve your chances of receiving a high quality index from a capable indexer? Here are seven tips that can help.

1. Find out about the indexer’s educational background. Does the indexer have a background of study in the subject matter of your book?

2. Ask for a sample index from the indexer. Is a sample index of a book similar to the one you are having indexed available? It would give you a good idea of the type of work she would do.

3. Look for a website. Does the indexer have a website? Many indexers do. A comprehensive indexer website can offer a ton of information about that person. Often indexes completed can be viewed from the website. You will certainly be able to see how the indexer presents himself professionally.

4. Notice whether the indexer has indexed more than one book for the same client. Having indexed more than one book for the same client is a positive sign, showing that a publisher or author was willing to hire this same indexer again.

5. Look for references or testimonials. Does the indexer have references available easily, or have positive testimonials from previous clients?

6. Is the indexer a member of LinkedIn? LinkedIn can provide more information about this person’s background and qualifications.

7. Ask for the indexer’s client list. This gives you an idea of the quality of the books that have been indexed, and whether some of his clients are publishers or authors of good repute.

You will have a high likelihood of receiving a problem-free and well-written index if you have answers to the above questions that satisfy you.