Unlike Amazon’s AZW/MOBI format, EPUB is an open standard that is used in a growing number of ereaders including the Apple iPad, Barnes & Noble NOOK, and Kobo eReader, among others.

The standard itself is controlled and developed by the International Digital Publishing Forum (IDPF), which is a trade and standards association made up of most of the large publishing and consumer electronics companies including Adobe, Apple, Barnes & Noble, Google, Hachette, HarperCollins, McGraw Hill, and Random House, among many others. Notably absent is Amazon, which has chosen instead to develop and market its own proprietary formats.

As an open standard, EPUB offers the potential for greater compatibility and interoperability between the supporting players. In a perfect world, this would mean that consumers could read their EPUB-format books on any reader running the appropriate software. While this is true for non-DRM EPUB books (books without Digital Right Management), unfortunately, all major electronic booksellers implement some proprietary or third-party DRM scheme to copy-protect their EPUB books.

In practical terms, this means that if a customer purchases a DRM-protected EPUB-format book in the Apple iBookstore, for instance, they can only read the book on Apple hardware, such as the iPad or iPhone. Likewise, an EPUB-format book purchased from Barnes & Noble can only be read on devices approved by Barnes & Noble.

This is not to say that open standards, such as EPUB, are pointless gestures. Quite the opposite. As an open standard, companies and developers can adopt the system to create their own products. Open standards can therefore lead to significant innovation and, since many parties typically adopt the standard, to greater longevity and a more dynamic ecosystem for products based on the standard. In short, it would be very tough to make EPUB disappear overnight (even if key players failed).

Understanding EPUB Features

Similar to Kindle AZW/MOBI, you can add basic formatting to your EPUB books (including specifying bold and italic text) and organize your information as simple tables.

You can also include a table of contents (with hyperlinks), as well as internal cross-references within your books. You can further include color photos and illustrations throughout your book (as with AZW, the first image in your book is usually a full page cover).

EPUB also allows you to add audio and video to your books, as well as Digital Rights Management to protect your ebook from being copied without authorization.

Strengths

Because of the number of software and consumer electronic companies supporting EPUB, you have a larger set of tools from which to choose when creating your ebooks.

Plus, since EPUB is supported in more ebookstores, you can essentially create, upload, and sell the same EPUB-formatted ebook in several stores, a considerable time-saver. In comparison, you can only buy Kindle AZW/MOBI books in the Amazon ebookstore.

Weaknesses

Similar to the Kindle AZW format, EPUB offers limited support for typography and layout. Aside from that, EPUB has no serious additional limitations for current-style ebooks.

Our Recommendation

In addition to Amazon’s AZW/MOBI format, every publishing plan should include an EPUB-format release. As mentioned earlier, the good news is that once you produce an EPUB version of your book, it’s very straightforward to repurpose your work for multiple electronic booksellers and markets.

Similar to Amazon AZW/MOBI, the EPUB format is best for the following types of ebooks:

• Most fiction (novel and short story anthologies, article collections)

• Memoirs (with basic layout requirements for photos and illustrations)

• Most general non-fiction

EPUB is less well suited for the following types of ebooks:

• Textbooks

• Coffee table style photo books

• Other books that rely on layout to highlight or convey information