EPUB (electronic publication) is an e-book standard, by the International Digital Publishing Forum (IDPF), which consists of three file format standards (files have the extension .epub), described below. It supersedes the Open eBook standard. EPub is a free and open standard for "reflowable" content, meaning that the text display can be optimized for the particular display device.
Internally, EPub uses XHTML or DTBook (an XML standard provided by the DAISY Consortium) to represent the text and zip as a packaging format. EPub includes optional support for Digital Rights Management (DRM). EPub became an official standard of the International Digital Publishing Forum (IDPF) in September, 2007, superseding the older Open eBook standard.
App iBookCreator doesn't work. The app help people were ok but treated me like newbie giving me advice I'd already tried. Still I'm highly motivated to use it. If anyone has helpful hints let me know😍