A researcher found that online medical searches may be seen by hidden parties, and the data sold for profit. Stuart Kinlough/Ikon Images/Getty Images hide caption

itoggle caption Stuart Kinlough/Ikon Images/Getty Images

Jonathan Zittrain, co-founder of the Berkman Center for Internet and Society, says the right to be forgotten online is "a very bad solution to a real problem." Samuel Lahoz/Intelligence Squared U.S. hide caption

itoggle caption Samuel Lahoz/Intelligence Squared U.S.

Using Tor, or The Onion Router, enables users to hide their online activities. Advocates say the network protects the privacy of activists. But prosecutors say it's used extensively by criminals — and is making it harder for law enforcement to do its job. Daniel Acker/Bloomberg via Getty Images hide caption

itoggle caption Daniel Acker/Bloomberg via Getty Images

The four undergrads of the Diaspora team were given "a global commission to rebottle the genie of personal privacy" after scoring $200,000 in a Kickstarter campaign and support and mentorship from Silicon Valley's brightest. Henrik Moltke/Flickr hide caption

itoggle caption Henrik Moltke/Flickr

A Google data center in Council Bluffs, Iowa. Even online privacy advocates acknowledge that keeping personal data out of the hands of third parties is virtually impossible today. Connie Zhou/AP hide caption

itoggle caption Connie Zhou/AP

A promotional image from Renew shows one of its recycling/advertising kiosks in London. City officials asked the company to stop recording data about the phones of passing pedestrians. Renew hide caption

itoggle caption Renew

David Petraeus, then-CIA director, testifies before the Senate Intelligence Committee in January. Petraeus resigned Friday after acknowledging an extramarital affair. Karen Bleier/AFP/Getty Images hide caption

itoggle caption Karen Bleier/AFP/Getty Images