Whether you call them categories, subjects or genres, how you label your book is vitally important, perhaps especially so in these times of the digital marketplace. Being placed correctly in ebook stores and libraries can help in both regular searches and with discovery techniques such as “Similar Titles”.
The EPUB format has been developed to allow your work to be properly tagged with as many subjects as is necessary to describe the title correctly, allowing any ebook reading system to categorise your books appropriately.
If you’re creating your EPUB files manually then you’ll need to open the .OPF in your favourite text editor. Then inside the metadata tags you can add your subject tags.
Here are some example entries;
<dc:subject>Fiction</dc:subject>
<dc:subject>Comedy</dc:subject>
<dc:subject>Satire</dc:subject>
You can add as many subjects as you like, though it’s probably best to keep things focused–adding 50 tags will be just as bad as adding none.
The arbitrary keyword or phrase used inside the subject tag hasn’t been standardised by the IDPF, but I’d recommend using the BISAC, LoC (Library of Congress) or other standardised system.
At this point you probably think there’s nothing more to be said on the topic, however…
eReaders Don’t Use All Provided Genres
When you send your EPUB out into the wild you’ll be somewhat disappointed to find that many eReaders don’t display every subject you placed in the OPF file, if any at all.
There are no IDPF requirements stating that a reading system must use any or all of the subject tags for categorisation and if it does use them, then you’ll find that it’s usually just the first entry. In the example above this would be Fiction. Still, we should take the time to add appropriate genres now as you can fully expect that future eReaders will utilise them more fully.
So, along with choosing the correct genres to describe your work I’d also recommend you list them in an appropriate order, and with the understanding that at this time, only the first entry will likely be used to categorise your book.
Now this is very good information. I certainly wasn’t aware of this when I published my first ebub for “The Dreamer Dreamed”. According to the article directories, it falls under Health and Fitness, but it would also fall under Spirituality and Metaphysics, even Self-Help.
The whole point, of course, is to extend the value of your work so that more people can find what they are looking for.