New Snowden leak: NSA program taps all you do online
You've never heard of XKeyscore, but it definitely knows you. The National Security Agency's top-secret program essentially makes available everything you've ever done on the Internet — browsing history, searches, content of your emails, online chats, even your metadata — all at the tap of the keyboard. ...XKeyscore is its "widest reaching" system for developing intelligence from the Internet. 

NSA’s XKeyscore program has nearly limitless access to all Internet activity
PowerPoint training materials obtained by The Guardian show how analysts could use the system to mine sprawling agency databases consisting of a vast reservoir of data. At least 41 billion records were collected and stored in a single 30-day period in 2012, according to the report, which also says XKeyscore collects more than 20 terabytes of information daily, including emails, chats, social media interactions, and even browsing histories—all in real-time.