Electronic surveillance

In 2013, Edward Snowden was an IT systems expert working under contract for the National Security Agency when he traveled to Hong Kong to provide three journalists with thousands of top-secret documents about U.S. intelligence agencies' surveillance of American citizens.

Journalist Robert Draper writes in National Geographic that the proliferation of cameras focused on the public has led "to the point where we're expecting to be voyeur and exhibitionist 24/7."

In the book @War, Shane Harris reports that U.S. intelligence agencies, sometimes aided by corporations, are trying to dominate cyberspace. It's "changing the Internet in fundamental ways," he says.

PBS looks at the origins of the agency's surveillance program and the extraordinary steps top government officials took to give it legal cover and keep it hidden.

In Dragnet Nation, Julia Angwin describes an oppressive blanket of electronic data surveillance. "There's a price you pay for living in the modern world," she says. "You have to share your data."

Today's Internet users have become accustomed to stories of hacking, identity theft and cyberattacks, but there was a time when the freedom and anonymity of the Web were new, and no one was sure what rules — if any — applied to its use.

Whether it's logs of phone calls or GPS data, commentator Geoff Nunberg says it still says a lot about who you are: "Tell me where you've been and who you've been talking to, and I'll tell you about your politics, your health, your sexual orientation, your finances," he says.

Shane Harris, an author and journalist who covers intelligence, surveillance and cybersecurity for a number of publications, says that the revelations about the NSA from Edward Snowden are nothing new, and that such programs have a significant recent history in the United States.