The reader of an ebook faces the question: which reader software should I use? The creator of an ebook faces the question: which ebook format should I use? In neither case is there a universally “best” answer.

As business interests have scrambled to try to capture the ebook market, many formats have been introduced. This completely unregulated environment has created a certain amount of confusion and a lack of uniformity.

Ebook (or ebook or eBook) formats fall into some broad categories. First, those based strictly on their internal structure:

  1. epub (or ePub)
  2. PDF
  3. text (or txt)

Next, ebook formats based both on internal structure and the means to read them:

  1. iBooks (read exclusively on iOS devices)
  2. MOBI (Third party readers such as Stanza, FBReader, Kindle for PC and Mac, and STDU Viewer can open MOBI files.)
  3. AZW (used exclusively on the Amazon Kindle)

It is important to note that these categories are not mutually exclusive. That is, while one must use ibook reader to read an ibook, one can also use ibook reader to read epubs, pdf, and text files (but not MOBI or AZW formats). In general, the formats based strictly on internal structure are the most adaptable to the widest range of reader software. However, it is also true that ebook formats based on internal structure and the means to read them offer more bells and whistles: design options, interactivity, multimedia, etc.

(There are myriad other ebook formats; I list above only the most popular.)

Amazon, as the big player in the online shopping world, seeks to force its format on the world. Thus, if one buys an ebook on Amazon, it will be in a format readily on Amazon’s product: the Kindle.

Similarly, Apple (as the big player in the tablet market), seeks to force its format on the world. So, buying a book through the Apple store means buying a book in iBook format, readable on Apple’s reader product, which runs only on Apple devices.

All of these is rather unsatisfying. It is as if Apple (or Amazon)  decided only to release its books in the French language. If you can’t read French, then get French lessons! Oh, and Apple is the only French teacher in town.

In some respects, the iBook format stands apart.

Consider as evidence of this the fact that, these recent articles surveying ebook formats (via Google search) don’t even mention ibooks: 1, 2, 3, 4. This kind of general inquiry into the web reveals that the general internet population has resisted viewing ibooks as a significant ebook format. At most universities, Windows-based machines still dominate, and certainly Windows is the overwhelming platform for the less advantaged parts of the world. Further, ibooks (unlike epub, pdf, txt, etc.) isn’t a format that one can read online, cutting off another large chunk of the population. On the other hand, iBooks has created a format which offers the widest range of design features, making it attractive to book designers who want to create a book with style, multimedia, and other advanced features. Authors simply have to decide whether or not these features are worth the enormous shutting out of possible readers that goes along with the iBooks format.

Finally, it is important not to demonize Apple too harshly: Amazon had already initiated its attempt to corner the market, and Apple’s response was largely “business as usual.”

A somewhat onerous option that many choose is to create their book in multiple formats: a design-rich format for iBooks, and a widely useable epub format for other devices: this is the approach we are working toward for our Tobacco Study book, the goal being to produce an innovate ebook (through ibooks author) and a widely useable one (a reflowable version).