The Lost Art of the Index in Ebooks

When was the last time you used an index in an ebook? Maybe the better question is this: Have you ever used an index in an ebook? One of the challenges here is that most ebooks don’t have indexes, the result of the misguided notion that text search is a better solution.

Every so often I come across an ebook with an index. More often than not it’s just the print index at the end of the book, sometimes with nothing more than the physical page references that offer almost no value in a reflowable e-format.

Fiction represents a large chunk of ebook sales and those books generally don’t benefit from an index. The same is true for some types of non-fiction books. But for pure reference guides, in-depth how-to’s, and other works, an index can be pretty useful.

If you’re relying exclusively on text search in an ebook you have to know exactly what you’re looking for. More importantly, why do we settle for such a lame text search solution when we’re spoiled every day with powerful, relevance-ranked search tools like Google?

When you search for a phrase in an ebook the results are shown in chronological order. You see all the occurrences from the beginning of the book to the end. Imagine if Google worked that way. So when you type in a phrase Google tells you the first (oldest) site to use that phrase, then the next oldest site that used it, etc. Users would laugh and reject it, yet that’s exactly what we’re forced to accept in ebook search.

What I really want is relevance-based results. Show me the location in the book with the highest density of that phrase and prioritize occurrences of it in a heading over occurrences in body text. I’m sure there are other attributes that could be rolled into an effective ebook search algorithm but I’ll take just those two features for starters.

The other problem with relying on search instead of an index is that you lose the benefit of synonyms and related terms. An indexer takes all that into consideration so you’re much more likely to find everything you’re looking for with a good index than a simple text search.

I’m not lobbying for back-of-book indexes in ebooks like they appear in print books. That’s another aspect that needs to change when you go digital. I want to see index functionality right there on the page I’m reading. The trick here is to offer it in a manner that’s not disruptive for the reader.

Remember that article I wrote a few weeks ago with the video showing a vision for auto-enriched ebooks? The same UI approach described there could be used here. The content is initially presented in as clean a manner as ebooks are today. But when you tap the screen on your tablet all the phrases that are indexed magically change color or are denoted with some other UI effect (e.g., underline). Just tap the phrase you’re interested in and a pop-up appears with relevance-ranked index results. These would be presented in a scrollable list with each entry having a preview of the text from that location in the ebook. Make it easy for me to bookmark those entries right in the pop-up. The net result is a way to quickly and easily access a smarter index without having to leave your current location.

This feature doesn’t exist today because we’re still stuck in the print-under-glass era of ebooks. I’m optimistic that one or two of the popular reading applications will eventually add such a capability though and help us get beyond today’s model where we’re consuming so much dumb content on all these smart devices.