What is ePub?

EPUB (also know by: ePub, .epub, or other variations on capitalization) is a free and open standard for for eBooks (electronic books) maintained by the International Digital Publishing Forum (IDPF). The ePub file format was designed to be open (anyone can use it or create it) and reflowable (the text can be re-sized and re-arranged to suite whatever display it's being read on). Ideally, it will catch on as the standard for ebooks.

For more on the history of the ePub format, see Wikipedia's ePub page, and of course, the IDPF's page.

EPUB is an electronic book format that has become the industry standard, allowing eBooks that use this format to be read on a wide variety of eReaders, from dedicated hardware to desktop software to online based readers. Here are a few examples;

• Hardware
  • Apple iPad
  • Sony Reader (Pocket/Daily/Touch Edition and PRS-505)
  • Bookeen Cybook OPUS
• Desktop Software
  • Adobe Digital Editions
• Online/Web Browser Readers
  • ibis Reader
  • Bookworm
  • EPUBReader

Technology

The EPUB format allows publishers to produce and distribute a digital publication that offers consumers interoperability between software and hardware for unencrypted reflowable digital books.

In October 2007 the OPS 2.0 was elevated to an Official IDPF Standard. The “.epub” file extension is made up of XML files for reflowable digital books and publications. EPUB is composed of three open standards, the Open Publication Structure (OPS), Open Packaging Format (OPF) and Open Container Format (OCF) all produced by the IDPF (International Digital Publishing Forum).

In actuality, the “.epub” file is just a renamed ZIP archive containing the books files, either XHTML or DTBook, and along with a number of XML description and navigation files there are sometimes image/media files.