Surveillance can occur in different forms. But they all have in common that there is an organization that collects and evaluates information secretly. Surveillance technology can be defined as devices or systems which can monitor, track and assess the movements of individuals, their property, and other assets.
In history, there have been many examples for surveillance systems and organizations. It is not my intention to give an broad overview of these past organizations. I rather focus on some current aspects of national surveillance systems and global surveillance.