Your e-book may be tracking your reading habits. The major players in e-book publishing can easily track how much time you spend on a page, whether you take notes or underline, and how many pages you read at a sitting. They can also track what search terms you use to find that e-book in the first place.
Earlier this year California passed the “Reader Privacy Act” which makes it more difficult for law enforcement to gain access to people’s e-book reading habits. As of now there is no way to tell Barnes and Noble or Amazon not to track this information.
For more on this see: Wall Street Journal