Surveillance technology can be defined as devices or systems which can monitor, track and assess the movements of individuals, their property and other assets. Much of this technology is used to track the activities of dissidents, human rights activists, journalists, student leaders, minorities, trade union leaders and political opponents. A huge range of surveillance technologies has evolved, including the night vision goggles; parabolic microphones to detect conversations over a kilometre away; laser versions, can pick up any conversation from a closed window in line of sight; the Danish Jai stroboscopic camera can take hundreds of pictures in a matter of seconds and individually photograph all the participants in a demonstration or March; and the automatic vehicle recognition systems can tracks cars around a city via a Geographic Information System of maps.