Surveillance is the monitoring of behavior, activities, or information for the purpose of influencing, managing or directing. This can include observation from a distance by means of electronic equipment, such as closed-circuit television (CCTV), or interception of electronically transmitted information, such as Internet traffic. It can also include simple technical methods, such as human intelligence gathering and postal interception.

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 organizations to plan and commit crimes, and by businesses to gather intelligence on their competitors, suppliers or customers.

Surveillance can be viewed as a violation of privacy, and as such is often opposed by civil liberties activists. A liberal democracy may have laws which restrict domestic government and private use of surveillance. Authoritarian governments seldom have any domestic restrictions, and international espionage is common among all types of countries.

Concerns have been raised about surveillance with regards to the Internet of things. Where surveillance technology is used for identification, monitoring, location tracking or to gain access to buildings and networks.(Wikipedia)