EPUB Done Properly
An accessible EPUB and a broken one look identical to the eye. The difference is invisible structure that screen readers and braille displays either can or cannot navigate.
01The Format Is Already There
EPUB is built on HTML and CSS — the same languages that make websites navigable. Every heading, list and paragraph can be tagged by type, not just styled to look like one. A chapter heading marked as <h1> tells assistive technology what it is; text in a large bold font tells it nothing. Publishers already produce EPUB routinely, which means the infrastructure exists. The gap is practice: files are often assembled for visual appearance alone, and the semantic layer is left empty or wrong.
Three things separate a properly built EPUB from a superficially adequate one. First, reading order: the sequence in which a screen reader encounters content must match the logical sequence of the text. Sidebars, pull quotes and captions that float visually beside a paragraph are often encountered in the middle of a sentence if the reading order has not been explicitly set. Second, alt text for images: every image that carries meaning requires a written description, and every decorative image needs to be marked as decorative so assistive technology can skip it cleanly. Third, language metadata: the file must declare what language it is in so that text-to-speech engines apply the right pronunciation rules, especially for anything multilingual.
EPUB 3, the current version of the specification, also supports ARIA landmarks and the EPUB Accessibility specification — a formal set of requirements aligned to WCAG 2 that a file can claim conformance to and that distributors can verify. The machinery to audit a file exists: tools like Ace by DAISY run automated checks in minutes and flag structural failures a visual inspection would miss entirely.
None of this requires a separate accessible edition. A single well-built file works for everyone, which is what born accessible publishing means in practice. The reason most EPUB files still fail is not that the format cannot carry structure. It is that producing correct structure costs attention, and attention costs time.
What can go wrong — and what fixes it
From the register| Item | What it means |
|---|---|
| Reading order | the sequence a screen reader follows does not automatically match visual layout; it must be set explicitly in the file |
| Alt text | images without descriptions are invisible to non-visual readers; purely decorative images should be flagged so they are skipped |
| Language declaration | missing or wrong language metadata causes text-to-speech to apply the wrong pronunciation rules |
| Semantic tagging | headings styled to look large are not the same as headings marked as <h1>; only the latter is meaningful to assistive technology |
| EPUB Accessibility conformance | a formal claim that a file meets the WCAG-aligned standard, verifiable by tools such as Ace by DAISY |
A chapter heading marked as
<h1>tells assistive technology what it is; text in a large bold font tells it nothing.
More in Structure
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