It’s one thing to decide to publish digitally – it’s entirely another to choose what form of ebook you’re going to publish. Each format has a lot going for it. And frequently publishers (and self-published authors) choose to publish in several digital formats, rather than confining themselves to just one.
The most popular ebook format is, in fact, one of the oldest: the PDF. It renders reliably on just about any device. It also can duplicate the layout of a print title. And it’s widely used in the academic market.
Amazon Kindle is the next most widely consumed. It’s a proprietary format – it only works on Kindle devices or through Kindle apps. And Amazon controls their Kindle platform in much the same way Apple controls iTunes – it’s a “walled garden” .
EPUB is not a walled garden but an ISO standard. An EPUB file is interoperable, rendering on multiple devices in multiple applications. Ideally, an EPUB file will look the same in Adobe Digital Editions on your laptop as it does on your Nook. (There are occasionally minor differences from platform to platform.) Apple, Kobo, Barnes & Noble, Google, Sony, and Overdrive (for libraries) all use EPUB.
Another option for your ebook is enhancing it with audio, video, or other media, or linking from the contents of the book to external websites. Outside of Apple’s iBookstore, not many platforms support enhanced ebooks from within an app – such as Kindle or Nook. However, it is possible to create an enhanced ebook as a stand-alone app, and sell it through the Kindle App Store, or the Android App Store. (Apple discourages books-as-apps and likes the enhanced file to be sold as an iBook.)
Many publishers decide to publish in all of these formats – but do so in a staged approach. They begin with the Kindle file because the market there is largest, add EPUB shortly thereafter (because a single EPUB file can serve many markets), and follow on with PDF and finally an enhanced file.
