EPUB 3.3

EPUB® defines a distribution and interchange format for digital publications and documents. The EPUB format provides a means of representing, packaging and encoding structured and semantically enhanced Web content—including HTML, CSS, SVG and other resources—for distribution in a single-file container.

About EPUB 3.3

EPUB 3.3 is a revision of the EPUB 3 specification, which can be considered as a successor to EPUB 3.2. It is also the first W3C Recommendation of the EPUB series of specifications.

EPUB 3.3 is backward compatible with EPUB 3.2, insofar as any EPUB 3.2 document is also valid EPUB 3.3. In other words, moving from EPUB 3.2 to EPUB 3.3 does not require any changes to current publication workflows.

The W3C process of standardization entails a thorough review of the specifications by Member experts, including checking the specification’s impact on implementations for internationalization, security, privacy, accessibility, and conformity to other Web standards. These reviews led to a number of small but important technical changes such as additional features to address bidirectional text, and more precise specification of security related details for scripts. The standard also includes detailed guidelines for implementers on the possible privacy and security problems.

The Working Group has also created a comprehensive test suite that systematically tests all normative features of the specification.

EPUB 3 documents

Specifications

EPUB 3 is currently defined by the following specifications:

EPUB 3.3 [[epub-33]]: defines the authoring format and requirements for EPUB publications, comprising features such as the package and navigation documents, EPUB content documents, fixed layouts, media overlays, and the container format.
EPUB Reading Systems 3.3 [[epub-rs-33]]: defines the conformance requirements for EPUB 3 reading systems — the user agents that render EPUB 3 Publications.
EPUB Accessibility 1.1 [[epub-a11y-11]]: specifies content conformance requirements for verifying the accessibility of EPUB 3 Publications.

The recommendation-track documents include detailed change logs on the substantive changes since the previous official releases. See the change log for EPUB 3.3, EPUB reading systems 3.3, and EPUB Accessibility 1.1, respectively.

Notes

Although the following documents are informative, they provide guidance related to implementing the EPUB 3 specifications as well as define experimental features.

EPUB 3 Overview [[epub-overview-33]]: gives a high level overview of the main EPUB 3.3 concepts and terms.
EPUB Accessibility - EU Accessibility Act Mapping [[epub-a11y-eaa-mapping]]: aims to demonstrate that the technical requirements of the European Accessibility Act related to ebooks are met by the EPUB standard.
EPUB Accessibility Techniques 1.1 [[epub-a11y-tech-11]]: provides guidance on how to meet the EPUB Accessibility 1.1 [[epub-a11y-11]] discovery and accessibility requirements for EPUB publications.
EPUB Multiple-Rendition Publications 1.1 [[epub-multi-rend-11]]: defines the creation and rendering of EPUB publications consisting of more than one Rendition.
EPUB 3 Structural Semantics Vocabulary 1.1 [[epub-ssv-11]]: defines a set of properties relating to the description of structural semantics of written works.
EPUB 3 Text-to-Speech Enhancements 1.0 [[epub-tts-10]]: describes authoring features and reading system support for improving the voicing of EPUB 3 publications.
EPUB Type to ARIA Role Authoring Guide 1.1 [[epub-aria-authoring-11]]: provides guidance for publishers looking to move from the use of the EPUB 3 epub:type attribute to ARIA roles for accessibility.

How to Participate

The EPUB 3.3 specification is developed by the W3C EPUB 3 Working Group and is now maintained by the Publishing Maintenance Working Group. All Working Group activities are conducted in an "open source" manner: the EPUB 3 specifications' site is publicly accessible.

All comments on EPUB 3 specifications should be submitted via the EPUB 3 issue tracker hosted on GitHub. (NOTE: you must login via a GitHub Account in order to submit an issue.)