In espionage and counterintelligence, surveillance is the monitoring of behavior, activities, or other changing information for the purpose of influencing, managing, directing, or protecting people. This can include observation from a distance by means of electronic equipment (such as closed-circuit television (CCTV) cameras) or interception of electronically transmitted information (such as Internet traffic or phone calls). It can also include simple no- or relatively low-technology methods such as human intelligence agent 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, prevention of crime, the protection of a process, person, group or object, or the investigation of crime. It is also used by criminal organisations to plan and commit crimes, such as robbery and kidnapping, by businesses to gather intelligence, and by private investigators.