PRISM allows the National Security Agency (that should be changed to the "National Surveillance Agency") to collect the data. It would naturally follow that they would also have a program for searching through all that data.
A top secret National Security Agency program allows analysts to search with no prior authorization through vast databases containing emails, online chats and the browsing histories of millions of individuals, according to documents provided by whistleblower Edward Snowden.
"I, sitting at my desk," said Snowden, could "wiretap anyone, from you or your accountant, to a federal judge or even the president, if I had a personal email".
US officials vehemently denied this specific claim. Mike Rogers, the Republican chairman of the House intelligence committee, said of Snowden's assertion: "He's lying. It's impossible for him to do what he was saying he could do."
But training materials for XKeyscore detail how analysts can use it and other systems to mine enormous agency databases by filling in a simple on-screen form giving only a broad justification for the search. The request is not reviewed by a court or any NSA personnel before it is processed.
XKeyscore, the documents boast, is the NSA's "widest reaching" system developing intelligence from computer networks - what the agency calls Digital Network Intelligence (DNI). One presentation claims the program covers "nearly everything a typical user does on the internet", including the content of emails, websites visited and searches, as well as their metadata.
Analysts can also use XKeyscore and other NSA systems to obtain ongoing "real-time" interception of an individual's internet activity.
This newest bit of information comes just as senators like Ron Wyden are pressuring the intelligence community for an explanation. Hopefully, this will make it even harder for them to placate the upset politicians and public with empty assurances about how responsibly and legitimately they're snooping into our lives.
It's a fairly long article, but i highly recommend reading the whole thing to fully experience the horror and outrage.