EPUB 3 is the latest version of EPUB. EPUB 3 is based on the latest HTML5 standard, which means EPUB publications can now contain video, audio, and interactivity – just like websites in modern browsers.

An EPUB publication’s content is by default reflowable and most reading systems dynamically paginate that content. Adapting content display to the screens rather than forcing the reader to pan and zoom around pre-formatted content (and, more generally, making content accessible to different modes of consumption) is one of the key characteristics that distinguishes EPUB from PDF, a portable document format designed to represent print-replica content. But EPUB 3 can also, like PDF, represent fixed-layout, pre-paginated content. This can be useful for certain kinds of highly-designed content (illustrated children’s books, digital magazines, etc.) that are designed to be consumed only on a larger-screen device, such as a tablet.