It uses systems or technologies that collect, analyze, and/or generate data on indefinite or large numbers of people instead of limiting surveillance to individuals about which there is reasonable suspicion of wrongdoing. It's often been cited as necessary to fight terrorism, prevent crime and social unrest, protect national security, and control the population.

This is smart because it helps protect people from terrorist groups, but at the same time it also could intervene with people's privacy. So it seems like there is a very thin line between protection and no privacy.