Superbook is a native book format for the web.
It is an empty container for any kind of longform: books, novels, comics, magazine or anything that needs multi-page storytelling. Superbooks are websites that work offline using a ServiceWorker—meaning, they are static PWAs that you can publish, edit, update and collaborate on just like an ordinary website or blog. And the readers get to enjoy your book straight on the web along with their friends and other readers by taking advantage of page-level referential accessibility.
This had been deemed impossible on the web until now due to the previously held assumption of the requirement of reflow on traditional webpages to scale content.
Definition:
Superbook means superclass of an object like book.
The above definition, concept and almost entire specification of Superbook format follows from the definition of the most common form book:
“A book is a series of pages assembled for easy portability and reading, as well as the composition contained in it. The book’s most common modern form is that of a codex volume consisting of rectangular paper pages bound on one side, with a heavier cover and spine, so that it can fan open for reading.” — wikipedia
The Superbook format also draws a lot from existing e-book formats and modern day front-end techniques of the web. It adheres to web accessibility guidelines as per WCAG 2.1 (2018) though there are some areas where the challenges of the longform creep up over and above the coverage of WCAG. In general the path ahead for Superbooks will be to follow the Priority of Constituencies closely and test every fundamental issue of state, usability and design principles from a codex standpoint.
This implies picking up what works best on the live medium of web without falling prey to matching a physical book or a digital file, both of which live outside of web.