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” .