This white paper introduces EPUB-WEB, a vision for the future of digital publishing that is based on a fully native representation of documents within the Open Web Platform. EPUB-WEB achieves full convergence between online and offline/portable document publishing: publishers and users won’t need to choose one or the other, but can switch between them dynamically, at will.

http://w3c.github.io/epubweb/

Readium (EPUB3): https://github.com/readium/