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A nest of surveillance cameras

Surveillance means the hidden watching of someone or thing by any means possible.[1][2] Police and security forces may put a tap on to a person's telephone line to listen to the person's calls. Intelligence and security agencies are doing it when they put an electronic listening device, a bug, into a room.

Governments and the military have built large facilities designed to listen in to communications between other governments and military groups. For example the U.S. has a large base at Pine Gap near Alice Springs, Australia, which listens to communication signals from all over the world.

Eavesdropping is a similar idea, but refers to ordinary people in normal life. It means listening to things you aren't supposed to hear. It is a deliberate act, rather than simply overhearing someone else talking.

Surveillance methods

WWII aerial photo of the V2 rocket test stand at Peenemünde.
Soviet truck convoy carrying atomic missiles near San Cristobal, Cuba, on Oct. 14, 1962 (taken by a U-2)

Surveillance is the secret or hidden watching of people or things with a purpose.[3] That purpose may be crime prevention or general gathering of information for a polical purpose. The results of surveillance are sometimes called "intelligence". Surveillance collects information for police, intelligence agencies, military planners or commercial firms.

This may include observation from a distance by means of electronic equipment (such as CCTV cameras), or interception of electronically transmitted information (such as internet traffic or phone calls).

Surveillance may include simple, relatively low-technology methods such as human intelligence agents and postal interception. On the other hand, global surveillance is done by satellite cameras on a daily basis. Such satellites are called "reconnaissance satellite" or spy satellites.

The word surveillance comes from a French phrase for "watching over" ("sur" means "from above" and "veiller" means "to watch").[4][5][6]


  1. /sərˈv.əns/ or /sərˈvləns/
  2. OED
  3. Lyon, David. 2007. Surveillance studies: an overview. Cambridge: Polity Press.
  4. Minsky M; Kurzweil R . & Mann S. 2013. The society of intelligent veillance, Proceedings of the IEEE. ISTAS. Toronto, Ontario, Canada, pp13-17.[1]
  5. Clarke R. 1988. Information technology and dataveillance. Communications of the ACM, 31(5), 498-512.
  6. Michael K. et al 2010. Planetary-scale RFID services in an age of uberveillance. Proceedings of the IEEE, 98(9), 1663-1671.[2]