title_body: If I buy a Kindle Paperwhite do I have to get books from Amazon? If I have a kindle paperwhite, am I limited to books from Amazon?  Can I purchase or download books from other sources/retailers?
upvoted_answer: Kindle devices allow you to load non-Amazon files onto them; you can copy them directly to your device using a micro-USB cable, or have them sent to your device wirelessly, through Amazon's Kindle Personal Documents service.
  
  You are limited to the types of files supported on the Kindle: at present, these are .azw, .azw1, .txt, .mobi, and .prc. In addition, Kindle can read .pdf files (but these keep the pre-formatted paging and layout of the original file, rather than the dynamic/flowing text of an ebook.)
  
  It is extremely easy to convert files into Kindle-supported formats from other popular formats -- such as .epub files, Word documents, and web pages. Amazon's Personal Documents Service can help you with transfer and conversion, and Calibre is an extremely popular tool for ebook-management which provides such conversions easily. PDF files which are mostly text are also quite easy to convert to a supported ebook format.
  
  The one big wrinkle in the all-around compatibility I'm describing here is that books protected by DRM (a Digital Rights Management scheme), the DRM prevents it from being converted into different formats. So an ebook you buy at barnesandnoble.com, which is formatted and protected exclusively for the B&amp;N Nook e-reader, cannot be easily converted for the Kindle. 
  
  Many major ebook retailers rely on DRM to help "lock you in" to their specific device, platform, and store. So basically, ebooks you get at non-Amazon stores are unlikely to be compatible with the Kindle (unless they specifically note that the ebook has no DRM), whereas ebooks from other sources (e.g. the out-of-copyright classics at Project Gutenberg, or ebooks you create yourself using a service like Instapaper) should present no difficulty.