EPUB 3 and Accessibility – What Does This Format Offer Publishers?
Just a few years ago, for many publishers, EPUB was simply an "ebook format." The primary concern was ensuring that a book would open on an e-reader, feature a proper layout, and cause no issues during distribution. Today, the situation is different. There is an increasing focus not just on the format itself, but on the quality of a publication’s preparation, its adherence to standards, and its digital accessibility.
And this is precisely where EPUB 3 comes in.
A number of technical associations have grown up around this standard. For some publishers, EPUB 3 sounds like a "more advanced EPUB"—one that requires more coding and a more complex production process. Yet, its true significance lies in more than just the addition of special effects or multimedia. Most importantly, it offers something far more practical: the ability to create publications that are simultaneously modern, flexible, and accessible to a diverse range of readers.
And in practice, this means something very simple – a book has a better chance of working well where it will actually be read.
EPUB 2 and EPUB 3 – Where Does the Difference Actually Come From?
For many publishers, EPUB 3 sounds simply like a “newer version of EPUB,” but in practice, the difference is far more significant than the standard’s version number alone suggests.
EPUB 2 originated at a time when an ebook was primarily viewed as a digital equivalent of a printed book. While the format handled simple text and basic structure well, it had limited semantic capabilities and offered much weaker support for modern assistive technologies.
EPUB 3 was built with the modern web and contemporary digital publications in mind. It is based on HTML5 and offers significantly better support for semantics, navigation, multimedia, global languages, mathematical content, and compatibility with screen readers. EPUB 3 makes it possible to correctly mark up various elements essential for accessibility—such as footnotes, chapters, quotations, and the book’s navigational structure.
The difference is clearly illustrated by a practical example. In EPUB 2, a book might have looked fine visually, but to a screen reader, it would appear as nothing more than a long block of text. EPUB 3 makes it possible to build a publication that assistive technology can truly "understand."
That is why, today, practically all discussions about available e-books revolve specifically around EPUB 3.
EPUB 3 Is Not About “Special Effects”
When EPUB 3 is discussed, examples involving multimedia—such as embedded audio, video, animations, or interactive elements—frequently come up. While the standard does technically allow for these, the issue is that, from the perspective of day-to-day publishing work, they are not the most important aspect.
In practice, things that are less spectacular—yet fundamental to accessibility—carry much greater weight:
proper document structure,
HTML semantics,
ability to navigate through the book,
compatibility with assistive technologies,
flexible adaptation of content appearance.
It is precisely these elements that make EPUB 3 the primary standard for accessible digital publications today.
A Book That Is Genuinely Readable
One of the biggest changes that EPUB 3 has brought to the world of ebooks is a much better use of document semantics and structure.
In practice, this means that a book ceases to be merely an “arrangement of text” and becomes a logically structured publication.
A heading is a heading.
A footnote is a footnote.
The table of contents is interactive.
A quotation is a quotation.
To someone reading visually, this might seem insignificant—after all, everything "looks" much the same. For a screen reader, however, it makes a fundamental difference.
Assistive technology does not interpret a book the way a human does; instead, it analyzes the document's structure. If that structure is correct, the user can jump between chapters, browse headings, refer back to footnotes, or quickly get an overview of the publication's layout
And this is precisely where the difference between a well-prepared and a poorly prepared EPUB file becomes very clear.
Imagine an academic textbook spanning several hundred pages. If its structure is correctly marked, a user can navigate to a specific chapter or locate a required term in a matter of seconds. If, however, the book has been prepared solely with its "visual" appearance in mind—lacking any underlying logical structure—navigating through it becomes akin to scrolling through a massive document with no visual anchor points to hold onto.
This is especially important for people who use screen readers, braille displays, and other assistive technologies. For them, a good structure is not just a technical add-on; it is an integral part of the reading experience.
Accessibility Begins in HTML
One of the greatest advantages of EPUB 3 is that it is based on web standards: HTML and CSS.
For publishers, this means something very important: accessibility does not require creating separate "versions for the blind." Instead, it is possible to build a single publication that works for various user groups.
This is very close to the concept of universal design – instead of creating something for one specific case, we create something that works for the widest possible group of users.
Interestingly, this is precisely why EPUB 3 can leverage many solutions that have been developed for the internet and websites over the years. In practice, this means that insights gained from web accessibility have significantly influenced the development of accessible e-books as well. For publishers, this is a major advantage—there is no need to "reinvent" separate standards for digital books, as many best practices have already been developed and tested within the realm of HTML.
EPUB 3 and Reading Flexibility
In the world of print, the publisher has full control over the appearance of a book. In the digital realm, some of that control shifts to the user. EPUB 3 was specifically designed to support this flexibility.
A reader can:
adjust text size,
modify contrast,
use custom fonts,
change how content is displayed,
use dark mode or high-contrast mode.
For some publishers, this can be challenging, as it requires moving away from the mindset that "a book must look exactly the same everywhere." In a reflowable EPUB file, increasing the text size causes the content to adapt to the available screen width, with the page layout regenerating accordingly. Consequently, a book may appear different on a large monitor, an e-reader, or a small smartphone—and that is precisely the point.
In digital publishing, it is more important for content to remain readable and adaptable to the user's needs than to preserve an identical layout. EPUB 3 works best when its inherent flexibility is leveraged, rather than attempting to force an imitation of print.
EPUB 3 Does Not Guarantee Accessibility
It is very important to state this clearly.
The mere fact that a book is saved in the EPUB 3 format does not necessarily mean that the publication is accessible.
It is possible to create an ebook in EPUB 3 format:
lacking structure,
without alternative descriptions,
with chaotic code,
with non-functional navigation,
with elements that are completely inaccessible to assistive technologies.
Technically, it is entirely possible, but highly inadvisable.
The format discussed here offers the potential to do this well, but it is the publishing process that determines whether that potential is properly realized.
It’s a bit like a modern printing house. Simply having good tools doesn’t guarantee that a book will be well designed.
Can a PDF File Easily Be Converted into EPUB 3?
This is one of the most common questions that arises when digitizing books—and, at the same time, one of the most treacherous.
At first glance, it might seem that since a PDF file contains the entire content of a publication, one could simply "convert" it into an EPUB file. In practice, however, the matter is far more complicated.
PDF was designed primarily as a page-layout format. It is intended to preserve an identical layout regardless of the device or software being used. EPUB works the other way around—its content is meant to be flexible, adapting to different screens, settings, and assistive technologies.
This means that conversion involves more than just “moving the text.” The book’s structure must also be rebuilt.
Headings must once again become actual headings, lists must be restored as lists, tables as tables, and footnotes must regain their navigational logic.
If a PDF was prepared solely for visual presentation—lacking proper structure and tags—conversion very often produces a chaotic result: arbitrary text breaks, incorrectly identified paragraphs, lost semantics, or completely inaccessible navigation.
For this reason, a well-prepared EPUB 3 file is rarely created by automatically "converting a PDF"; instead, it requires working with the source material and properly building the publication's structure. Automated conversion may serve as a starting point, but it is seldom the final step in the process.
Why EPUB 3 Matters for Business Today
Until recently, accessibility was often treated as a niche or supplementary topic. Today, it is increasingly becoming a standard part of quality.
Publishers more and more often encounter requirements from public institutions, expectations from digital libraries, the need for compliance with accessibility regulations, and demands from technology partners and distribution platforms.
And this is precisely where EPUB 3 begins to take on significance—not just technologically, but also strategically.
Because a well-prepared, semantic, and accessible EPUB file:
it is more future-proof,
it works more easily with various devices,
it integrates better with supporting technologies,
it has a greater chance of remaining useful despite technological changes.
What Exactly Do You Use to Open EPUB Files?
This question comes up surprisingly often—among both readers and publishers themselves.
EPUB does not work like PDF, which can be opened in much the same way almost anywhere. To read books in this format, you need an application or a device that supports EPUB files.
On computers, programs such as Thorium Reader, Adobe Digital Editions, or Apple Books (on Macs) are frequently used. On phones and tablets, popular applications include PocketBook Reader, Apple Books, and Google Play Books. Meanwhile, ebook readers—such as those from Kobo or PocketBook—support the EPUB format natively.
It is worth keeping in mind that different applications may interpret the same book in slightly different ways. This is precisely why publishers test their publications across several environments—a book can look and behave differently depending on the software or device being used.
From an accessibility perspective, applications that are compatible with assistive technologies are also of great importance. One of the most highly recommended solutions is Thorium Reader, which works very well with screen readers and is frequently used for testing accessible EPUB files.
EPUB 3 Is a Way of Thinking About the Digital Book
However, the most significant change does not concern the format itself.
It concerns a shift in mindset.
EPUB 3 makes it very clear that a digital book is not just a "paperless PDF." It is an environment in which the reader can engage with the content in a variety of different ways.
Some will read using their eyes.
Others will listen via a speech synthesizer.
Someone might read a book on their phone while on a train.
Someone else might use a braille display.
Accessibility is not about creating separate books for each of these people.
It is about creating a single publication that can adapt to different ways of reading.
And that is precisely why EPUB 3 has become the foundation for modern, accessible ebooks today.
Bibliography:
https://swiatczytnikow.pl/kilka-porad-dla-wydawcow-od-bookosfery/
https://elektroniczneksiazki.pl/jaki-format-e-booka-wybrac-epub-mobi-pdf/
https://www.w3.org/TR/epub-overview-33/
https://www.edrlab.org/open-standards/epub/
https://www.quora.com/What-are-the-advantages-of-ePUB3-conversion-for-publishers
About the Author
Monika Zarczuk-Engelsma
Content Creation Specialist at the Polish Foundation for the Blind and Visually Impaired “TRAKT”
Has a degree in Polish philology (Academy of Podlasie) and a postgraduate diploma in Partner Marketing and Public Relations (University of Gdańsk). Took part in projects concerning learning to use a computer by blind individuals, conducted training on volunteer programmes for blind people, was part of the European Voluntary Service project (organised by the EU) and received an internship offer at the European Economic and Social Committee. In her daily life she uses braille, but also an Iphone with voiceover and a laptop with a speaking screen reader. This enables her to achieve a high degree of self-reliance and she is able to function in the way that suits her best: spend time on active and interesting activities, meet new people, work, read books, or pursue her hobbies, i.e. chess, board and card games and travelling. She has already visited more than 30 countries.
