Every book you read on your Kindle (or Kindle app) and every word you highlight in those ebooks is recorded by Amazon and may be shared by the bookselling behemoth with the federal government.
The Guardian (U.K.) explains how the agents of the surveillance state are surreptitiously storing all the annotations readers make in electronic copies of books:
Just take a look at the Kindle terms of use. As you wrestle with the rantings of Austria's most lethal watercolourist [Adolf Hitler], your device is providing Amazon with "information related to the Digital Content on your Kindle and Supported Devices and your use of it ... such as last page read and content archiving". It's also reporting back on information "including annotations, bookmarks, notes, highlights, or similar markings", and may be storing those reports on "servers that are located outside the country in which you live" — say hello,...