In a12-minute video on The Guardian's website, Edward Snowden, a former technical assistant for the CIA talks about how American surveillance systems work and why he decided to reveal that information to the public.
Last week, news of an NSA program to monitor American citizens' communication became public knowledge.
Over the weekend, the leaker was revealed as former CIA employee Edward Snowden.
Major tech companies like Google and Yahoo! have claimed to know nothing about the program, but there's speculation that might not be the whole truth.
While a lot has been leaked, there's still a lot we don't know.
Here to talk about what we do know about PRISM is New York Times reporter Eric Lichtblau. He's also the author of the book Bush's Law: The Remaking of American Justice.