Leaked documents give new insight into how NSA scours data globally

London: Documents published by the Guardian are providing new insight into how the National Security Agency scours the world's data, giving readers an over-the-shoulder look at the way in which American intelligence analysts exploit the hundreds of billions of records they gather each year.

Dozens of slides published by the newspaper divulge details about XKeyscore, one of a family of NSA programs of which leaker Edward Snowden says has given America the ability to spy on "the vast majority of human communications."

Some of the slides carry screenshots appearing to show what analysts would see as they trawled the intercepted conversations.

How and from where the program draws its data isn't completely clear, but the slides say XKeyscore is supported by 700 servers and 150 sites across the globe.