On Which E-Readers Can the Kindle Format Be Read?by John Lister
Although Amazon advertises its Kindle e-reader as allowing you to start reading in 60 seconds, it is worth taking a couple of minutes to think through your e-book options before making a purchase. Not all electronic book files work on all electronic reading devices. The format for books bought via the Kindle store is particularly restrictive, and the workarounds that do exist have some limitations.
Electronic books bought from Amazon -- whether on the Kindle itself or through the Amazon website -- are in the AZW or KF8 format. These are proprietary formats, meaning they are created by Amazon itself and not shared with other companies. The formats are almost identical to a more widely used format called MOBI. The two differences are that the Amazon formats have improved compression, meaning the same book is smaller in AZW or KF8 format, and that they have digital rights management copy protection enabled. KF8 files support the HTML tags used in websites to control layout and appearance. By default, an AZW or KF8 file can only be accessed on Kindle devices or through Kindle reading applications on other devices. Rival electronic readers cannot read an AZW or KF8 file directly.
Conversion and DRM
A range of third-party applications can convert electronic book files from one format to another, such that the book can be read on a different electronic reading device. The big problem is that a simple conversion does not work on files that carry DRM copy protection. This is because DRM requires a match between a particular book file and a particular device that is licensed to display that book. Amazon currently allows publishers to decide if a Kindle book should carry DRM. Amazon's listing for Kindle books do not specifically say whether or not a book carries DRM.
It is possible to read Kindle books on other devices through a dedicated reading application from Amazon. This app effectively treats the other device as if it were a Kindle for licensing purposes. Users can even read a book on both a Kindle e-reader and another device running the app and synchronise their position within the e-book.
The Kindle apps are available for Windows PCs and Macs; iPhone, Android, BlackBerry and Windows Phone 7 smartphones; and iPad and Android tablets. This means it's possible to read Kindle books through the app on Barnes & Nobles' Nook tablets, but not its standalone Nook e-readers.
It is possible to read electronic books in other formats on the Kindle itself. To do this you can add the file to your Kindle by connecting it to a computer and running your file management software such as Windows Explorer. You can also e-mail the file to a dedicated address which is listed under your account settings on the Amazon website.
As well as AZW format, the Kindle can display MOBI, PDF, PRC and TXT files added in this way. Several other formats including DOC and HTML only work if you send them via the e-mail address; Amazon then converts them before delivering them to your Kindle.