The EPUB specification is a distribution and interchange format standard for digital publications and documents. EPUB defines a means of representing, packaging and encoding structured and semantically enhanced Web content — including HTML5, CSS, SVG, images, and other resources — for distribution in a single-file format.

EPUB has been widely adopted as the format for digital books (ebooks), and these new specifications significantly increase the format’s capabilities in order to better support a wider range of publication requirements, including complex layouts, rich media and interactivity, and global typography features as well as a high degree of accessibility.

However, it must be emphasised that it is indeed possible to create an unaccessible EPUB 3 if these features are not employed. The publisher must ensure that the format is used to its best advantage in this respect.


The EPUB specification is maintained and managed by the Publishing@W3C Group. Information concerning the various working groups, how you can participate, the standards and profiles is available at the Publishing@W3C site together with details on the various technical specifications of the EPUB formats and its profiles.

EPUB Accessibility 1.1 Specification

The EPUB Accessibility specification references accessibility conformance and discoverability of EPUB files. The specification is structured so that there is a set of universal high-level requirements, while a separate techniques document identifies specific practices and how they are implemented in the different flavours of EPUB.

See our guidance page for some useful top tips on creating accessible EPUB files and how you might make the most of some of the above features


The DAISY Consortium has released a free, open source EPUB accessibility checking tool, Ace by DAISY, which has been created to assist in the evaluation of conformance to the EPUB Accessibility Specification. Designed to assist content providers at any stage in their workflow, Ace by DAISY makes it easier to produce higher quality, more accessible EPUB content files that meet internationally recognized standards.

For more detailed information on the EPUB specification see our Developers page on Inclusive Publishing