New revelations in the British newspaper The Guardian offer an in-depth description of XKeyscore. It's a top secret National Security Agency program that collects the emails, social media activity and browsing history of individuals, including US citizens.
Author James Bamford says the program has an exceptionally broad reach.
"I don't think this is one little group of people that are doing it," he says. "Everybody at NSA has this as one of their tools."
Bamford notes that XKeyscore was first revealed in the British newspaper Der Spiegel several weeks ago.