EZepub.com

EPub format is a container or packaged format like a '.zip' file that holds file elements in organized folders making up a document intended to be read via an ereader such as the iPad.

From Wikipedia:

 EPUB (short for electronic publication; alternatively capitalized as ePub, EPub, or epub, with "EPUB" preferred by the vendor) is a free and open e-book standard by the International Digital Publishing Forum (IDPF). Files have the extension .epub. EPUB is designed forreflowable content, meaning that the text display can be optimized for the particular display device used by the reader of the EPUB-formatted book. The format is meant to function as a single format that publishers and conversion houses can use in-house, as well as for distribution and sale.

 From IDPF:

 ".epub" is the file extension of an XML format 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), produced by the IDPF. "EPUB" allows publishers to produce and send a single digital publication file through distribution and offers consumers interoperability between software/hardware for unencrypted reflowable digital books and other publications. The Open eBook Publication Structure or "OEB", originally produced in 1999, is the precursor to OPS.

 Packaged XML (for short)

 XML (eXtensible Markup Language) = a web standard with representation of arbitrary data structures in mind.

EPub folds together a structure of a book as if it were a portable website directory.

• Text may be parsed for easier loading and navigating by the device
• Styles have its own subfolder
• Graphics have a folder, and so on