The NSA (National Security Agency) has some 24,000 employees and the ability to monitor just about all the electronic communications on the planet (in addition to taking pictures with spy satellites). But in practice, that's way too much information for even the NSA to handle. What the NSA does instead is monitor specific phone numbers (or areas, from neighborhoods to entire small countries) and listen (or look) for specific words or phrases. The United States gets about 75 percent of its useful intelligence from the NSA, but the organization is not nearly as efficient as movies (or even some media reports) would lead you to believe. The NSA has to deal with hundreds of languages and dialects, and getting stuff translated is often a time consuming process. To narrow its focus and increase its chances of finding something worthwhile in time to be useful, the NSA depends on the FBI and CIA to tell it where to look, or listen. With 800 million cell phones in use at the moment, and half a billion email accounts worldwide, focus is important. The NSA is not so much a security agency as it is a service agency. And it's service is picking up phone conversations or email that might be of use to the FBI and CIA.