Compatibility of Kindle, iPad and B&N Nook Reader Files

Although an e-reader may be capable of reading different types of files, each device is designed primarily for the e-books available from the manufacturer's e-bookstore. Amazon sells e-books in MOBI format, while Apple and Barnes & Noble sell e-books in EPUB format. If you think that should make Nook e-books and iPad e-books compatible with each other, you might almost be right. Each manufacturer embeds code in their e-books, making them incompatible with other readers.



Nook and iPad EPUB Formata

The Barnes & Noble Nook and the Apple iPad's iBook app are designed to read e-books in EPUB format. The EPUB standard was developed by the International Digital Publishing Forum. Text and images are encoded and packaged into a single file using Web-based formats like XHTML and CSS. Even though the e-books you purchase from Apple iBooks or Barnes & Noble use the same format, this doesn't mean they are compatible. Each online bookstore includes Digital Rights Management (DRM) software encoded into the books, preventing them from being opened by different e-book readers.

Kindle MOBI Format

The Amazon Kindle is the only major e-reader designed for MOBI format e-books. This format was created by Mobipocket, a company purchased by Amazon in 2005. The format is similar to EPUB in that it is based on HTML and packages text and images into a single file, but is incompatible with e-readers designed for the EPUB format. All e-books purchased from Amazon.com are in MOBI format, although they usually have a .AZW file extension.

Cross-Platform Apps

Books purchased from Apple's iBookstore can only be read using the iBooks app, available on the iPad, iPhone and iPod Touch or with iTunes on a Windows or Mac computer. Both Amazon and Barnes & Noble also have apps available on Apple products, including the iPad, as well as on Android and Windows smartphones, tablets and computers. So if you buy an e-book from any of these companies, your choices are not limited solely to that company's e-reader.

Converting Formats

Provided an e-book is not DRM-restricted, any EPUB file can be read on an iPad, a Nook or any other major e-reader except the Amazon Kindle. Conversion programs like Calibre, which is free to download, can convert MOBI or EPUB files to formats designed specifically for different e-readers including the Kindle, iPad and Nook. Free e-book resources like Project Gutenberg, which offers free copyright-expired e-books, often make versions available in both the MOBI and EPUB format.