Summary: EPUB 3 is the standard format for digital books, with support for accessibility, interactivity and universal compatibility. Moving from EPUB 2 to EPUB 3 is an essential step for publishers who want to stay relevant.
Moving from EPUB 2 to EPUB 3 is a decisive step for publishers who want to stay relevant today. EPUB 3 is more than a version bump: it is a fundamental change in how digital books are conceived, produced and read.
For publishers still working in EPUB 2, understanding what EPUB 3 offers is essential to making sound decisions about their digital catalogues and about how they deal with readers and distribution platforms.
EPUB 3 and HTML5: the universal language of the web
One of the most significant changes in EPUB 3 is the adoption of HTML5 as its markup language. Where EPUB 2 used XHTML 1.1, a more limited specification, EPUB 3 takes up the full range of HTML5 and CSS3, the same technologies that underpin the modern web.
In practice that means an EPUB 3 book can use the same visual and structural resources available on any modern website. Advanced typography, flexible layouts, semantic elements and native multimedia support are only some of what opens up with the move.
Compatibility with web standards also makes production easier. People who know HTML and CSS can produce high-quality digital books without having to learn proprietary or publishing-specific technologies.
Better accessibility
Accessibility is one of the pillars of EPUB 3. The EPUB Accessibility specification, built into the standard, sets clear criteria for producing digital books that people with different needs can use, including visual, hearing, motor and cognitive disabilities.
EPUB 3 natively supports alternative descriptions for images, a semantic heading hierarchy, navigation through landmarks, a logical reading order and compatibility with assistive technology such as screen readers. None of that existed in any standardised form in EPUB 2.
In Brazil, where the PNLD programme requires digital educational material to meet accessibility criteria, EPUB 3 is the format that best answers those regulatory demands.
Richer metadata
EPUB 3 widens what is possible with metadata considerably compared with EPUB 2. With support for vocabularies such as extended Dublin Core and additional ONIX properties, a book's content can be described far more richly and precisely.
Accessibility metadata, copyright information, detailed publication data and even subject classifications can all go directly into the EPUB 3 file. That metadata improves how well the book is found on retail platforms and makes cataloguing in digital libraries easier.
At a time when search engines and AI assistants use metadata to recommend content, having publications with rich, standardised metadata is a significant competitive advantage.
Richer design and interactivity
EPUB 3 allows publications with a sophisticated design that goes well beyond running text. With full CSS3 support you can use custom fonts, gradients, shadows, subtle animation and complex multi-column layouts.
Beyond visual design, the format supports interactive elements such as embedded audio and video, JavaScript for controlled interaction, and SVG content for scalable graphics and illustrations. These are particularly valuable in textbooks, children's publications and technical material that benefits from visual and interactive demonstration.
It is worth stressing that interactivity in EPUB 3 should be implemented as progressive enhancement. The main content of the book must remain accessible even when JavaScript is unavailable, so that the reading experience never depends on advanced features.
Conclusion
Migrating from EPUB 2 to EPUB 3 is not only a technical matter. It is a strategic decision that affects the quality, accessibility and longevity of a publisher's digital list. EPUB 3 offers a modern technical foundation, aligned with web standards, that allows richer, more accessible and more future-proof digital books.
For publishers who have not yet started this transition, now is the time. Distribution platforms already favour EPUB 3, the PNLD programme requires accessibility standards that EPUB 2 cannot fully meet, and readers expect increasingly sophisticated digital experiences.
Booknando specialises in producing digital books in EPUB 3 with a focus on quality and accessibility. If your publishing house needs support with this transition, get in touch.
