Ebook Formats for Ebook Readers
WHAT YOU SHOULD KNOW ABOUT EBOOK FORMATS
The most popular ereader on the market today is Amazon's Kindle. A recent survey by market research company IDC found that 48% of all ereaders sold worldwide in 2010 were Kindles.
Even though the primary platform for reading Amazon's ebooks is the Kindle, Kindle-formatted ebooks can be read on nearly every mobile device, computer and tablet thanks to Amazon's free cross-platform Kindle software and Kindle Cloud Reader webapp.
All Kindle versions support Amazon's .azw format, unprotected .mobi, .txt and .prc file formats natively, and the newer models support PDF documents as well.
When it comes to ereading devices, Amazon's Kindle is not without competition. And in terms of the format of the ebooks it natively accepts, it's the odd man out.
Most other ebook devices including the Kobo (formerly favored by Borders, and still heavily sold in Canada through Chapters-Indigo), Barnes and Noble's Nook, and the Sony Reader all accept ebooks formatted in .epub format.
Because EPUB is the most widely-used standard, and Amazon includes a very efficient conversion program called KindleGen for EPUB files, creating your ebook in EPUB format is the best first-step in making your ebook available to all retail channels.
WHAT IS AN EPUB BOOK?
EPUB is a free and open standard for ebook formatting by the International Digital Publishing Forum (IDPF). The IPDF is the trade and standards association for the digital publishing industry. It's member companies encompass most major publishers, publishing, bookseller and library associations, small and mid-size publishers and other stakeholders.
EPUB files usually have an .epub extension after the filename, and are simply "containers" for the multiple content, image and style pages that make up a book.
EPUB, like AZW, is designed for reflowable content, which means that the text of your ebooks can be optimized for the particular device it's being read on. This is in contrast to PDF formats, which are designed to hold the exact same format no matter how wide, narrow or small the screen.
DIGITAL RIGHTS MANAGEMENT AND EPUB
While EPUB is an open standard based on XML, that doesn't mean that it doesn't support digital rights management (DRM). EPUB does not require a DRM-wrapper, nor does it specify one particular type of DRM to use. Instead, it allows publishers to choose their own preferred DRM provider and specify rights with a rights.xml file at the top level of the compressed file.
Currently, the most popular DRM solution for EPUB books is Adobe's Content Server.