A good book index is, as Sam Leith writes, “a map of the text; a cunningly devised series of magical shortcuts that can…save a scholar many hours of work.” An index can be a work of art in its own right, leading readers to view the work in new and useful ways. But why do publishers make such a big deal about indexes, and what do you need to know? I talked with some indexer colleagues about what we, as professional book indexers, wish authors knew about the indexing process. Here’s the inside track on the list in the back.

1. Yes, you really do need an index (even for e-books!)

People really do look at the index when considering whether to buy a book. Potential buyers (including distributors, bookstore buyers, scholars, and librarians) check for more than just whether the book deals with a particular topic they’re interested in. They peruse it as a guide, a far more detailed map than the table of contents or a quick browse can provide.

A book’s index can, as Harold Macmillan once said, “give a far clearer glimpse of its spirit than the blurb-writers or critics are able to do.” It’s also a mark of serious scholarship that’s designed to be part of a body of research. A book with an index is a book that means business.

“Indexes make sense for print books,” I’ve heard it argued, “but why bother now that we have searchable e-books?” Because the map an index provides is still profoundly helpful. Because clickable indexes make using the index easier than ever. Because you can only search for what you know is in the text—an index lets you discover what you didn’t know was there and how it’s related to what you’re looking for.

In fact, when you can’t just flip the pages, indexes and book indexers are more important than ever. And because in the age of digital information, as indexer Barbara Quint puts it, “If you don’t index it, it doesn’t exist.”

2. No, a computer can’t index your book

As indexer and cartoonist Iva Cheung points out, “Well, it can try, but the index’ll be unusable.” What fully automated programs can do is generate a concordance, which is just a list of words that appear in the text (so unless you think your reader cares how often the is used, you can skip this).

Indexing involves much more than searching for keywords, and not everything belongs in the index! A keyword search or concordance program will find every instance of “George Washington,” but it’s not going to tell you what the book says about Washington or how he relates to the book’s themes. It won’t weed out a mention of the George Washington Bridge or a passing idiomatic reference to lying about chopping down cherry trees. Authors often allude to topics of interest indirectly or use different terminology to refer to them, which won’t show up in keyword searches.

So if Washington appears more than once or twice in the book, a keyword search will just yield a long list of uncontextualized page numbers. And as for those overarching themes that run through the book without necessarily being called out by a keyword on every page—forget about it. For that, you need a human brain.

3. There IS professional indexing software, but it’s not automated

Useful indexing software does indeed exist, but it’s not the fully automated concordance-maker that used to be bundled into word processing programs.

Professional book indexers invest in software programs like Sky Index, Cindex, or Macrex, all of which automate the slower and more tedious elements of indexing—like alphabetization, abbreviating page ranges, and autocompleting previously added entries—without analyzing the text itself. That’s left entirely to the indexer, who analyzes the book’s structure and themes. As Leith notes, “Indexing is a work of interpretation; it is, however humble in the service of its object text, a work of intellectual scrutiny.” More recent versions of Microsoft Word do offer a way to use bookmarks to generate a real index, but it’s wildly laborious and even more time-consuming than the old-fashioned method of using index cards.

Good indexing software is quite expensive and involves a steep learning curve, just as indexing itself does. If you’re thinking about buying software and attempting to index your own book, do yourself a favor and put that money toward hiring a professional instead. They’ll already have the software—and better yet, they know what to do with it.

4. Indexing is harder than you think

Analytical work is at the heart of the indexer’s profession. Indexers parse not only what’s in the book but how it’s all related and what the readers of a book in that specific field will be looking for (this is why indexers usually specialize in particular fields or topics). As indexer Sylvia Coates has put it, “Indexing requires special skills. It’s both a craft that can be learned and an intuitive art that involves a way of understanding, conceptualizing, and organizing a book.”

Book indexers have to be mind-readers: we put ourselves in the reader’s shoes to predict how they will look for information within the text (and yes, that’s going to be very different from how you, as the author, would do so).

Who’s approaching this text, and why? Will the terms they look for be different from the ones the author uses? Academic authors often coin new terminology and get very excited about it—but someone who hasn’t read the book yet is unlikely to know your new coinage and might need another path to find that information.

Do Mi Stauber, author of the indexing handbook Facing the Text, notes that “for any given indexable concept, there are likely to be several possible wordings, as well as several different main entries in which the locator could be included.” Finding the most intuitive phrasings and using them consistently is a big part of indexing.

Because academic publishers usually put the responsibility for indexing on authors, it can be tempting to try to do it yourself (or, let’s be real here, to ask a graduate student to do it). But if you ask untrained authors who’ve tried this, they’re likely to respond with a shudder and a thousand-yard stare. Indexing isn’t easy—and the index a nonprofessional is capable of producing will be far less useful for readers (and much more of a headache) than one produced by people who write indexes for a living.

5. Budget for a professional—and book ahead

Indexing isn’t cheap. Once you know how much skilled work goes into the process, though, it quickly becomes clear that this is one of those times when you’re better off paying a professional, just as you’d pay a plumber or an electrician to work on your home rather than risk the damage of an amateur job going badly.

You can find professional book indexers here at Ideas on Fire or search the directories of professional organizations, like the American Society for Indexing and the Editorial Freelancers Association. Most indexers charge by the page, by the entry, or by the hour, and rates vary depending on specialization and experience. Expect to pay $1,000–2,000 for a quality index.

You’ll also want to book your indexer well in advance. Most academic publishers allow three to four weeks for page proofs to be proofread and indexed (separate processes that usually run simultaneously), and good book indexers are often booked months ahead of time. You may be required to put down a deposit to hold your spot on the indexer’s calendar.

It’s also important to make sure that your book is in its absolutely final form before beginning the indexing process—that is, you won’t be adding or cutting any more text. Even minor changes can force the indexer to start from scratch if the book’s pagination changes (and, yes, that’ll cost you).

Once you receive your index draft, it’s okay to ask for revisions from your indexer (that’s what we do here at Ideas on Fire). Why ask your indexer instead of making corrections yourself? As indexer Stephen Ullstrom notes, authors don’t always know how to make revisions correctly. (Two of the biggest errors authors introduce to indexes? Using hyphens for page ranges when they need to be en dashes, and messing up the very carefully crafted cross-reference schema.) At Ideas on Fire, this is why we ask you to send us your requested revisions; we then implement them before sending you the final index. Your indexer understands the practices and conventions publishers require and will make sure that no errors are introduced in the revision process.

Indexing is a world of its own within the publishing industry. It’s not for everyone, but those of us whose brains happen to be wired for it find it an interesting and rewarding way to engage with texts and help readers connect with authors. A quality index for your book is an investment that pays off.