The government can use its data programs to track people's movements and even their personal interests, McClatchy News reports.
Anytime you use your smartphone to post something like a picture to the Internet, you can be giving away your location to the government.
That's because your cell phone contains GPS location information and computers can use that data to figure out where you were when you put that picture online.
"People don't realize how much information they're giving out," said Karen Reilly, the development director for The Tor Project, a U.S.-based nonprofit that produces technology to provide online anonymity and circumvent censorship.
"You can try to secure it - you can use some tech tools, you can try to be a black hole online - but if you try to live your life the way people are expecting it, it's really difficult to control the amount of data that you're leaking all over the place," she warned.