EPUB (short for Electronic Publication) is a widely used open standard for digital books and publications. It’s developed by the W3C (World Wide Web Consortium) and is designed to be reflowable, scalable, and accessible, making it a flexible format for reading across devices and for users of all abilities.
📘 What Is EPUB?
File Extension: .epub
Based On: XHTML, CSS, and X
ML
Core Strengths:
Reflowable text: Content adapts to screen size and user preferences.
Interactivity: Supports multimedia (audio, video), links, and JavaScript.
Accessibility-friendly: Built-in structure supports screen readers and other assistive technologies.
🔍 Why EPUB Is Important
Cross-platform support: Works on most e-readers (Apple Books, Kobo, Calibre, etc.), tablets, and phones.
Accessibility: EPUBs can be made highly accessible, often more so than PDFs, due to their HTML-like structure.
Customization: Readers can adjust font size, color contrast, and layout for a better experience.
✅ Accessibility Features of EPUB
EPUB 3 (the latest major version) was specifically designed with accessibility in mind:
Semantic Markup: Uses HTML5 elements for structure (headings, lists, tables).
Navigation: Built-in table of contents, landmarks, and page navigation.
Alt Text: Support for image descriptions using alt, aria-describedby, or extended descriptions.
Media Overlays: Synchronize text with audio (like read-aloud books).
MathML Support: Proper rendering and accessibility of mathematical content.
ARIA Roles: Enhances support for assistive technologies.
Language Declarations: Identifies language of content for accurate screen reader pronunciation.
🛠️ How to Create Accessible EPUBs
Authoring Tools:
Word + WordToEPUB (DAISY tool)
Sigil (free EPUB editor)
Pressbooks, Adobe InDesign, or Pandoc
Structure Content Properly:
Use headings, lists, and semantic HTML elements.
Add Metadata & Accessibility Info:
Specify title, author, language, and accessibility features (using ONIX or schema.org).
Check for Accessibility:
Use the ACE by DAISY tool – an EPUB accessibility checker.
Manual testing with screen readers (NVDA, VoiceOver, etc.)
📦 EPUB vs PDF: Accessibility Comparison
Feature EPUB PDF
Reflowable Layout ✔ Yes ✘ Often fixed
Built-in Semantics ✔ HTML5-based ✘ Requires tagging
Screen Reader Ready ✔ With good markup ✔ If properly tagged
Adjust Text Size ✔ Easily ✘ Limited
Responsive Design ✔ Optimized for all screens ✘ Usually fixed layout
🚦 EPUB Accessibility Standards
EPUB Accessibility 1.0 (by W3C)
WCAG 2.1 – EPUBs should comply with the same web accessibility standards
EPUB 3.3 – Latest version with stronger accessibility metadata and authoring guidance
Would you like help converting a document to EPUB or checking the accessibility of one?