Social network analysis

One common form of surveillance is to create maps of social networks based on data from social networking sites such as Facebook, MySpace, Twitter as well as from traffic analysis information from phone call records such as those in the NSA call database,[38] and others. These social network "maps" are then data mined to extract useful information such as personal interests, friendships & affiliations, wants, beliefs, thoughts, and activities.[39][40][41][42]
Many U.S. government agencies such as the Defense Advanced Research Projects Agency (DARPA), the National Security Agency (NSA), and the Department of Homeland Security (DHS) are investing heavily in research involving social network analysis.[43][44] The intelligence community believes that the biggest threat to U.S. power comes from decentralized, leaderless, geographically dispersed groups of terrorists, subversives, extremists, and dissidents. These types of threats are most easily countered by finding important nodes in the network, and removing them. To do this requires a detailed map of the network.[41][42][45][46]
Jason Ethier of Northeastern University, in his study of modern social network analysis, said the following of the Scalable Social Network Analysis Program developed by the Information Awareness Office:

The purpose of the SSNA algorithms program is to extend techniques of social network analysis to assist with distinguishing potential terrorist cells from legitimate groups of people.... In order to be successful SSNA will require information on the social interactions of the majority of people around the globe. Since the Defense Department cannot easily distinguish between peaceful citizens and terrorists, it will be necessary for them to gather data on innocent civilians as well as on potential terrorists.
—Jason Ethier[41]

AT&T developed a programming language called "Hancock" which is able to sift through enormous databases of phone call and Internet traffic records, such as the NSA call database and extract "communities of interest" -- groups of people who call each other regularly, or groups that regularly visit certain sites on the Internet. AT&T originally built the system to develop "marketing leads",[47] but the FBI has regularly requested such information from phone companies such as AT&T without a warrant,[47] and after using the data stores all information received in its own databases, regardless of whether or not the information was ever useful in an investigation.[48]

Some people believe that the use of social networking sites is a form of "participatory surveillance", where users of these sites are essentially performing surveillance on themselves, putting detailed personal information on public websites where it can be viewed by corporations and governments.[39] About 20% of employers have reported using social networking sites to collect personal data on prospective or current employees.[49]