) is the monitoring of the behavior, activities, or other changing information, usually of people for the purpose of influencing, managing, directing, or protecting them. This can 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); and it can include simple, no- or relatively low-technology methods such as human intelligence agents and postal
interception. The word surveillance
comes from a French phrase for "watching over" (sur
means "from above" and veiller
means "to watch"), and is in contrast to more recent developments such as sousveillance.
Surveillance is used by governments for intelligence gathering, the prevention
of crime, the protection of a process, person, group or object, or the investigation of crime. It is also used by criminal organizations to plan and commit crimes such as robbery and kidnapping, by businesses to gather intelligence, and by private investigators.
Surveillance is often a violation of privacy
, and is opposed by various civil liberties
groups and activists. Liberal
democracies have laws which restrict domestic government and private use of surveillance, usually limiting it to circumstances where public safety
is at risk. Authoritarian government seldom have any domestic restrictions, and international espionage is common among all types of countries.