If evolution is the cornerstone of life, that’s certainly no less true in the electronic world. If you can’t adapt — or fail to adapt in time — you’re destined to join the ranks of the Netscape Navigators, OS/2 operating systems, and WordPerfect office suites of the world, as a warning to future technology developers that nothing lasts forever, and never in its original form. In this light, EPUB 3 is more than just bug fixes and tweaks from the last version; it represents a major change in what an ebook can be. It’s a whole new beast, you might say.
The ebook market has been going through its own kind of hyper-evolution in the mere four years since EPUB2 was released, and a flurry of new devices and document formats have come and gone in that time. E Ink technology was all the rage in 2007 when Adobe, Amazon, Sony, and others were entering the market, however, and EPUB2 arrived to meet the new needs of these portable reading devices, with improved presentation capabilities, better navigation, support for DAISY accessibility features, and some advances in global language support. But EPUB2, like its predecessor and contemporaries, remained a static format, in that its core only allowed for the reading of basic text and image documents.
EPUB2 was an advance, and for a time it served the needs of the market well. It might even have had a longer run had dedicated E Ink devices remained the predominant choice for reading. But just as readers were abandoning their paper books, tablet computers came storming onto the reading scene, not only adding visual and aural dimensions lacking from E Ink’s shades of gray, but also including the appeal of merging many capabilities into a single device — reading, browsing, gaming, and music, to name just a few. Dedicated E Ink readers suddenly didn’t seem so cool anymore, nor did bland content that looked just like a printed page.
Although the primary effect of this new progression in the way content is read was to expose the multimedia shortcomings of current formats, ebook content had been under assault for a variety of other reasons, too. The ebook community had been clamoring for the ability to make interactive content, for improved global language support, and for better accessibility features, as well as a whole host of other changes to the status quo.
The International Digital Publishing Forum (IDPF) would have been foolish to sit tight on the EPUB2 specification in the face of its own constituents’ needs, so a revision was inevitable. Unlike Amazon’s Mobi format for its Kindle devices, which is able to rest on its progressively aging technology because both the content and rendering are tightly controlled by a single company, EPUB requires the IDPF to take a much broader perspective with its development because of its diverse community. But this requirement has also kept the format at the leading edge of ebook technologies throughout its history. While EPUB2 was, to use a common euphemism, good for its time, that time, dominated by the initial thrust of reproducing the static print page in electronic form, has passed.
[Note: Amazon's Kindle Format 8 will reportedly include some amount of HTML5 support.]
EPUB2 didn’t suffer only from the lack of new features that HTML5 now offers; not every problem a format faces can be solved by new technology alone. Accessibility is one obvious example in EPUB2. In retrospect, the way that features of the DAISY standard got bolted onto the specification led to aspects never being fully or properly implemented by publishers or developers (the DTBook grammar for content) and others being misunderstood or conflicting with general-purpose needs (the NCX navigation file being used for reduced tables of contents, undermining its use by the target audience). The EPUB 3 revision also presented a chance to revisit issues like these that had appeared or been left open since the previous revision, to see if new and better solutions were now possible.
The EPUB 3 working group began the revision of the specification in the summer of 2010 and had a one-year timeline to overhaul the format, in order to address all these issues and more. The result is that the revision has seen major improvements in virtually all the key functional areas: integrated audio and video support (as we’ve mentioned), accessibility features are much more tightly entwined in the specification now, global language support mechanisms are more numerous and also more integrated, publication-level metadata allows much richer expressions, and so on down through the original charter.
This isn’t to suggest that the EPUB 3 revision got everything perfect. The metadata world is in flux, and many had hoped that a more standards-oriented solution would be forthcoming. Video content support is divided between the H.264 and WebM codecs, leaving the specification without a single video type that all reading system developers could agree to support. The comic and manga communities still are looking for more improvements in supported formats and rendering. In other words, the evolution of EPUB doesn’t end with the current revision, and thought is already going into improvements.
That said, if you want an open, community-driven, standards-compliant specification that sits at the forefront of what an ebook can offer, however, there is no other solution but EPUB 3.