Choosing an eBook Format (Part II)

.mobi / .prc / .azw for Amazon Kindle

Mobipocket (also .mobi, .prc, or .azw) is specific to the Amazon Kindle. Mobipocket is also supported on handheld devices and eReading applications. But, most importantly, it is the only format accepted by Amazon.

A .prc is a data file used in mobipocket formats. This file type can be saved with DRM copyright protection that limits the devices on which the file can be opened. PRC stands for Palm Resource Code file.

A file with the .mobi extension is a mobipocket ebook file. The mobipocket ebook format is based on the Open eBook standard using XHTML and can include Javascript and frames.

Mobipocket was bought by Amazon in 2005. With the launch of the Kindle ebook reader, Amazon created the proprietary format AZW. It is based on the Mobipocket standard with its own DRM formatting.

The Kindle is a great choice for authors because it is so easy to publish your books to the Kindle Direct Publishing platform, and because the Kindle is one of the top selling stand-alone eReading devices to date. The ease of use, not only in publishing to the platform but also for readers to access and download your work, make this an ideal choice for authors choosing to self-publish and maintain control over the entire process, from start to finish. Authors do not need a middle-man or aggregator in order to publish to Amazon’s KDP. Authors can also use Amazon’s automatic conversion tools to convert their document to a Kindle book (.mobi or .prc, a proprietary format); however, the online converters in existence everywhere so far will only do so much. The conversions are not always pretty, and they are not typically meant for books that have more complex content. (See our comparison table for a list of design elements categorized by device.)

The Kindle doesn’t support much in the way of enhanced styling (especially for the non-tech-savvy). In order to format your work yourself, you need knowledge of HTML, XHTML, and CSS—Regular Expressions and possibly even PEARL sometimes come in handy for extremely difficult or lengthy material—to get a great result. This format does not natively support color, images wrapped to text, fancy styles, drop caps, or much else in the way of sophisticated formatting. However, there are tricks to get it to do more—raised caps, small caps, images and tables with captions, horizontal rules, and more. There is a bit of a learning curve for these things. It’s normally recommended that if the work contains complex elements, authors should consider hiring a professional ebook designer.

In general, the accessibility of the Kindle Direct Publishing platform, as well as the sales of the reader and ebooks via Amazon itself, make this format an excellent choice for authors.

At-a-glance: Drawbacks to Amazon’s Kindle

• Proprietary file type that cannot automatically be read on competing devices
• Supports color only on the Kindle Fire
• Does not support a wide variety of fonts or special styles

At-a-glance: Benefits to Amazon’s Kindle

• The Kindle Direct Publishing platform makes it simple for authors to upload and publish their content; books are available for sale in a short period of time
• The Kindle now supports library lending, with a note-taking feature
• The Amazon Kindle is a very popular eReader, and it is very easy for readers to download content—making it easier for readers to access your book
• Amazon will automatically link your print version (if available for sale on Amazon) with your Kindle version
• Royalty amounts are very reasonable if authors opt-in to their lower pricing scheme

ePub for B&N Nook, Apple iPad, Sony, and Almost Everything Else

ePub is an open industry ebook format. This is the format used by Apple, B&N, Sony, Kobo, and Diesel (among others). This format offers the widest range of distribution options. “ePub” is the file extension of an XML format for reflowable digital books and publications. This package of files is composed of three open standards: the Open Publication Structure (OPS), Open Packaging Format (OPF), and Open Container Format (OCF), produced by the IDPF. You may learn more than you probably want to know about these items here:

http://www.openebook.org/2007/ops/OPS_2.0_final_spec.html

These files are essentially “zipped” files, so you may view the contents of an ePub file by changing the file extension to .zip (in Windows) and then extracting the contents of the file.

These files include
MIMETYPE
META-INF
OEBPS

There are a number of good resources available on the web in order to understand the contents of each file. (A working knowledge of XHTML and CSS is a MUST for the highest quality result. If you are formatting in MSWord or Adobe InDesign, you must also have at least a basic knowledge of the “styles” function of each software type.)

Currently, the ePub format can be read by the Kobo eReader, Apple iBooks, Barnes & Noble Nook, Sony Reader, BeBook, Bookeen Cybook Gen3 (with firmware v. 2 and up), COOL-ER, Adobe Digital Editions, Lexcycle Stanza, BookGlutton, AZARDI, Aldiko and WordPlayer on Android and the Mozilla Firefox add-on EPUBReader.

Adobe Digital Edition uses the .epub format for its ebooks, with DRM protection provided through their proprietary ADEPT mechanism. (Although the recently developed INEPT framework and scripts have been reverse-engineered to circumvent this DRM system.)

The ePub format also tends to support more design options. It is more flexible and encompasses more platforms; however, it is not readable on the Kindle. You must first convert the ePub to an acceptable Kindle format. Also, books that are going to be sold via retail channels such as the Apple iBookstore must pass an ePub validation check. This can be troublesome without help if it fails to pass.

Almost all of the items listed in our comparison table for designers are possible in the ePub format, although most of the complex elements require XHTML and CSS, at minimum, in order for the complex formatting elements to properly display. However, not all devices that read the ePub format may display all of the elements listed. For instance, the first-generation Nook does not support color.

Aside from greater flexibility in design, the benefit of using the ePub format is that it also encompasses a wider variety of online retail outlets, including the Apple iBookstore. (See Choosing an eBook Publisher/Aggregator). The ePub format is also used by Barnes & Noble, who is the second highest bookseller of ebooks, and their Color Nook is also now very popular. The great thing about the Color Nook is that it opens the door to authors of children’s books or comic books—essentially material where color is actually an integral part of the story. If color is necessary, you will want to choose the ePub format.

At-a-glance: Drawbacks to ePub

• There are three commercially available ePub standards: Sony, B&N, and Apple. It’s not one format due to DRM restrictions. Meaning that once your ePub file has DRM applied to it via the distribution source, you cannot take the file to other devices, even if it does support ePub. Amazon, on the other hand, is one company, one standard, one DRM—you know what you’re getting into.
  If you buy a book through iBooks to read on your iPad, the added DRM will keep you from being able to read the book on your Sony Reader or on the Barnes & Noble Nook, even though all of these devices support the ePub format.
• The validation process can be extremely difficult for more complex content, and all ePub books to be sold by online retailers such as Apple must pass validation.
• Just because ePub is accepted by multiple retailers does not mean that the file looks the same or works the same on every device. In addition, you might have to go through multiple channels in order to sell your one ePub file on the Apple iBookstore in addition to the Barnes & Noble Nook or the Sony Reader. This makes it more difficult to get published, and more time consuming to learn the rules and requirements for each retail outlet.

At-a-glance: Benefits to ePub

• Book design options are far greater, and more complex layouts can be maintained
• ePub is accepted in more places and can be read on more devices (with the caveats listed above)
• ePub files are normally accepted for library lending (*Note: Kindle books are now also available for library lending)

Conclusion

Our recommendation, of course, is to have them all. The more formats in which your book can be purchased, the greater your chances of increasing sales, this includes print, PDF, Kindle, and ePub. In addition, the one benefit to having your work designed outside of general conversion software (or platforms that promise to convert your work to all formats with one go) is that you then have the option to customize your work to your primary target devices. For instance, you can have your work formatted specifically for Amazon’s Kindle, the Barnes & Noble Color Nook, and the Apple iPad, in a way that takes advantages of the strengths of each device. While an ePub file will work on both the iPad and the Nook, the iPad can support more sophisticated design elements, and offers a two-page spread view in landscape orientation. It could be worth taking advantage of this design flexibility by having a separate ePub created just for the iPad.

However, if you can only afford one format above print, you would want to choose the format that works best for your specific content.

• If the book must be in color, or if the layout itself is more complex and you want the ebook version to support more design options, you would want to consider ePub.
• If it doesn’t matter whether the book is in color, and you really want the ease of being able to publish your book directly to Amazon and have it ready to buy and very accessible via the largest online retailer in the world, in a very short period of time, then the Mobi/PRC for Kindle option is best.
• If it is critical that your design remain static, or if you have media intensive content (and you expect your audience to view your material on their PC, print it on their computer, or perhaps view it on the iPad or Android Tablet, then you may want to choose an active PDF.
• Finally, if your work is fairly basic, then there’s no reason you can’t use a mass-conversion option to convert your work for all platforms at once.

For details on publishing your book, see the following:

How to Publish Your Book on the Amazon Kindle
How to Publish to the Barnes and Noble Nook Using PubIt!
How to Publish on the B&N Nook and Apple iPad Using Smashwords
How to Publish on the Kindle, Nook & iPad using BookBaby.com
How to Publish on the Apple iPad using iTunes Connect
How to Publish on the Apple iPad using Lulu.com