Government surveillance programs point up new data-mining concerns.
But the NSA monitoring programs focus on collecting "meta" data—not the actual procedures you've undergone, but merely the records of things you searched for online, or people you telephoned.
What can this metadata reveal? Plenty about your health, experts argue; simply knowing who you're calling can be just as revealing as what you say.
If you can track a series of calls, one privacy expert tells tells the New Yorker's Jane Mayer, "you know exactly what is happening—you don’t need the content.”