There may have been truth to Edward Snowden’s controversial claim that he said he could “wiretap anyone” if he had their email address. The Guardian has revealed a training guide for a program called XKeyscore, which NSA documents call the agency’s “widest-reaching” system for gathering Internet information. The program monitors everything anyone does on the Internet, from the content of emails to websites visited, searches, chats, and metadata. It can also be used to watch real-time Internet activity. The quantity of data collected is so huge—1 billion to 2 billion records a day—that they can only be stored for several days, with more “interesting” data saved for longer. Though an NSA worker would need a warrant to target a U.S. citizen, the agency can collect data on any citizen in communication with someone on foreign soil without a warrant.