What is the Epub Format?

convert to epub format

The ePub Format for Ebooks

Epub is a free and open ebook standard for formatting ebooks. The name Epub comes from “electronic publication”. Epub files have the extension .epub.

With the exception of Amazon the major ebook stores including Apple iBookstore, Sony Reader Store and Barnes & Noble Ebookstore are primarily publishing ebooks in the epub format.

Ebooks in the epub format are readable on most ebook readers including Barnes & Noble Nook, Sony Reader, Kobo eReader, Android devices,  Apple iPad/iPhone, etc.

Epub files are not automatically readable on the Kindle so if a Kindle owner wants to read an ebook that is only in the epub format they would need to convert it first, for example from Epub to Mobi format which the Kindle can read.

Epub became an official standard of the International Digital Publishing Forum in September 2007, superseding the Open eBook standard (which Mobi format is based upon).

The key features of ePub format include:

  • Free and open standard
  • Re-flowable (word wrap) and re-sizable text
  • Inline raster and vector images
  • Embedded metadata
  • DRM support
  • CSS styling

Because Epub is designed for reflowable content, the text display can easily be optimized depending upon the display device used.

This is an advantage over some PDF documents, for example, especially those created several years ago, as the text could not always be wrapped to fit smaller screens on mobile devices.

What’s in an epub file?

An epub file is essentially a zipped file containing a combination of xhtml documents, packaging files (including information about the individual files and sequence, and the author and publisher) and container files for encryption and digital rights management.

See also How to get an Ebook into the ePub Format.

About the Author: Gary McLaren

Gary McLaren is the author of 'The Indie Author's Guide to Publishing Ebooks'. He also manages several web sites for professional writers including Publish Your Own Ebooks and Worldwide Freelance.


  1. jake kizziar says:

    …what is the best and fastest way to get my books to ebook status? With all the e chatter, it can be very confusing.

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