Index in a Book: How to Write and Format an Index

In the digital age, you might think that old-school research done in a library with a stack of books is a thing of the past. After all, if you can just pull up a search bar and type in what you're looking for, why would you need a book index? Thanks to indexers and detail-oriented authors, a well-done book index is often better than the results from your favorite search engine.

And if you're a nonfiction author, you may want to add an index to your book. Read on to learn how as we explore how to write and format an index in a book. 

What is a Book Index?

A book index is a collection of terms in alphabetical order that point the reader to the page number (or numbers) where the associated information can be located. Indexes (or the less-used “indices”) are more common in certain types of nonfiction than in fiction. Textbooks and other information-heavy books are where you'll often find “bob” (back-of-book) indexes. 

The main purpose of an index is to make things easier for the reader. While the table of contents takes a high-level view of the book, usually just listing chapter numbers and headings in the order in which they appear, indexes are different. Using an index, the reader can look up a certain term and find the pages where that term is located in the book. This makes it easy for them to reference only the information they need without spending a lot of time trying to locate the right section by skimming. 

Does Your Book Need an Index?

Not every nonfiction book really needs an index. Narrative nonfiction books, such as memoirs, don't usually have an index. However, this is not to say that all narrative nonfiction books don't. Many that require heavy research from many sources include indexes as well as a list of references. 

In fact, most nonfiction books could include an index to help the reader. This includes things like cookbooks, self-help, personal finance, true crime, and many more kinds of nonfiction. 

If you have a publishing contract, it will be up to you and your publisher whether you include an index in the book's back matter. If you're self-publishing, ask yourself whether an index would benefit your readers. If the answer is yes, then it's a good idea to include one. 

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Your Options for Writing an Index

You don't need any special skills or training to write an index for your book. However, you may want to consider hiring an indexer to do it for you. It really depends on whether or not you want to tackle the job. It can be time-consuming and you need an eye for detail. 

A good index is intuitive because the indexer keeps the reader in mind at all times. If the book is aimed at a general audience, the key entry terms will take this into account by using terms and headings that a general audience is likely to use when looking up information. On the other hand, if the book is written for an audience already familiar with industry terms, then the index will reflect this. 

Of course, as the author of the book, you're in a good position to index it yourself. Whereas a freelance indexer will have to read the book multiple times, you've (presumably) already done so. You know the book better than anyone. So it's just a matter of going through and deciding what to put in the index and what to leave out. But even with all this in mind, it can take many hours to complete an index. 

What Should You Include in the Index?

Book indexing takes a familiarity with the subject matter and an eye for detail. It also involves making judgment calls. Sometimes, it can be hard to know what to put in the index, and what to leave out. 

For example, sometimes authors mention certain subjects in passing as a way to illustrate their point. A professional indexer will determine whether that subject should be included in the index or not. Most of the time, if the subject or term is only mentioned in passing and doesn't contribute significantly to the overall subject, then it won't be included. 

Once again, this all comes down to knowing the reader. If the reader is likely to want to know more about a subject, or they're likely to come back to it, then it should be included in the index. 

Likewise, authors don't always explicitly mention a term in every section. They may discuss a term or subject in detail without ever actually referring to it by name in that section. Proper book indexing means locating these areas and creating the proper key term for them in the index—and using the key term the reader is most likely to search for.

Cross References in an Index 

You'll also need to be familiar with cross references. These are entries in the index that point the reader to other entries with the words “See” or “See also.” If someone is looking for information on a certain subject, the index can include that heading, but point the reader to a different section that discusses the subject. 

So you see, although it doesn't take any special training, indexing books takes hard work. If it's the type of hard work you like, then you should absolutely index your own book (or become a professional indexer!). 

How to Go About Indexing a Book

We've discussed what indexers do, but in this section, we'll talk about how they do it. There are a few ways to go about indexing a book. Different indexers use different ways. Some of them use indexing software to help them out, while others use index cards to keep everything straight. Many use a combination of both. 

As you can tell from the discussion above, indexing can't simply be done by software. It needs a human to guide it through the creation of the index by highlighting certain content in the body text. 

Since most people are familiar with Microsoft Word, we'll first discuss how to use the built-in indexing software in Word, then we'll discuss the index card method. 

Creating an Index in Microsoft Word

Creating an index in Word is fairly straightforward. Just follow the steps below to index your document or manuscript. 

Step 1: Highlight and Mark

To start off, simply locate a term or phrase you would like to index. Highlight the term or phrase and then navigate to the References tab at the top toolbar. Near the right side of the tab, you'll see the index section. Simply select Mark Entry. A window will pop up on your screen.

Step 2: Get Specific

From here, you can decide whether you want to bold or italicize your entry, as well as whether to create it as a cross-reference. Most notable here is the option to Mark All. If it's a term or phrase repeated throughout the text, then you may want to select Mark All so the software will automatically pull all page numbers to put in the index later.

If you want to capitalize the index entry, you'll need to do it from the Mark Index Entry window that pops up. However, reference your style manual (like the Chicago Manual of Style) to determine whether this is necessary. Some style manuals suggest that the entry shows up in the index exactly as it does in the content.

Also, you may want to add a subentry in this window if there's another heading related to the one you're currently indexing. It's a good idea to acknowledge the relationship between entries, even if the subentry has its own heading elsewhere in the index. 

Step 3: Paragraph Formatting

Note that when you mark an entry for your index, Word will automatically switch over to showing paragraph marks. To get rid of this, simply navigate back to the Home tab and deselect the paragraph marks button. But know that each time you mark an index entry, it will do this again. 

Step 4: Insert Index

Once you have all your index entries done (or all that you want to do right now), you can insert your index. To do this, bring your cursor to the spot in the document where you want your index. Create a header and then click Insert Index in the Index section of the References tab. 

If you end up adding or removing index entries, you can also update the index by clicking on it and then selecting the Update Index option. This will automatically update the alphabetical list to reflect any changes you made. 

Using Index Cards

Some authors prefer to use index cards to keep track of all possible index subjects and headers while writing their book. This doesn't negate the need for creating an index in the digital manuscript, but it may be an easier way to keep track of things as you go instead of doing it all at once after the book is edited.

If you go this route, make sure to update each index card with the correct page numbers and subentries as well. 

Creating Multiple Indexes

If your book has images, maps, graphs, or tables, you may want to create a separate index for each category. This can make things easier for the reader, allowing them to navigate quickly to the section they need by referencing the right index in the back of the book. 

Index in a Book: Conclusion

Although an index is a simple alphabetical listing of important terms in a book, writing one can take some time. If you're an indie author, you'll need to decide whether your index needs a book at all. If it does, then you'll also need to determine whether you'll do it yourself or hire someone to do the indexing. 

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