What is EPUB 3?

EPUB and Web Standards

The importance of web standards to EPUB has been mentioned a few times now, so before jumping into all the new features of EPUB 3, it’s worth a brief diversion to look at why this integration with the browser stack (XHTML, CSS, and JavaScript) is so important to the format.

Saying that EPUB is tied to the browser stack is not to suggest that, back in 1999 when the first version of the specification was released, the Internet Explorer and Netscape Navigator browsers of the day were the intended reading targets. It simply means that the same open standards that underpin the World Wide Web were seen as both a natural fit for digital reading and integral to the long-term survival of the format. They were a natural fit because HTML had already swept the landscape as the king of reflowable content—that is, as a format that scales easily to the viewing area available on any device, unlike fixed formats like PDF that rely on exact positioning—and they were integral to the long-term survival of the format because, even in 1999, there was little doubt that the Web was here to stay.

Being tied to the browser stack has also provided a number of technical advantages that have helped EPUB thrive while other formats have ingloriously come and gone from the landscape. For one, it has simplified the development of reading systems because rendering engines like Gecko and WebKit have been readily available to expedite the process (a rendering engine is the same core that browsers ...