Electronic Books are becoming more and more popular with the success of eReaders like Amazon’s Kindle and the emergence of tablet computers. Although many readers still prefer paper, eBooks take up less space, are often cheaper, and can provide reading enhancements like flexible font sizing and multimedia. One of the most daunting hurdles to readers that are new to eBooks is the wide array of eBook formats. Here are three that are worth paying attention to:
The .pdf format was developed by Adobe Systems as a way of preserving document layout across computing platforms. Short for Portable Document Format, .pdf files emulate the traditional structured layout of print books. As a result, it is an excellent format for publications that require tight control of layout, fonts, and images, such as legal or technical documents. The price of this level of precision is a limited ability to resize and reflow text. Originally a proprietary format, Adobe has made .pdf available as an open standard. PDF files are also easily viewable desktop computers using free software like the Adobe Reader.
The .azw format is the propriety format used by the Amazon Kindle eReader. All eBooks purchased from Amazon’s Kindle Store are delivered in this format, which includes a proprietary Digital Rights Management system that requires users to use a Kindle or Kindle software. Amazon has made its Kindle software available for desktops, smartphones, and tablets, allowing readers to read their books on any device. Unlike the .pdf format, .azw files are “reflowable” and allow readers to adjust the font size, background color, etc., of their eBooks. The Kindle and Kindle software will also read the legacy format on which .azw is based, called Mobipocket (.mobi). Many books at Project Gutenberg are available in this format.
The .epub format is an open standard developed by the International Digital Publishing Forum. ePub files are reflowable and allow readers to adjust the font size, background color, etc., of their eBooks. The IDPF hopes to finalize the ePub 3 standard by mid-2011, which will include support for embedded video and audio. ePub files are supported by several devices including the iPad, Barnes and Noble Nook, Borders Kobo, and the Sony eReader. The Google Books project and Project Gutenberg both offer books in .epub format.
A note on Digital Rights Management (DRM)
All three of the eBook formats discussed here can come with a variety of proprietary digital rights management encoding that may limit which files may be read on which devices.