"Surveillance" comes from a French word that means "to watch over;" camera surveillance uses photography to watch over people in public spaces. In the United States we are used to them in public areas such as stores; in London, there are over 200,000 cameras. Most were installed in the 1980s and 1990s, in an effort to deter Irish Republican Army (IRA) bombers.
Others, concerned with privacy rights, worry about whether people's right to privacy is being invaded, or whether capacity to survey crowds may encourage racial or other profiling.
Nevertheless, the federal government did put surveillance cameras on its list of must-have counterterrorism technologies following the September 11 attacks. State and local governments are following suit. In 2005, New York City contracted Lockheed Martin to install 1,000 surveillance cameras on its subways. Chicago has installed over 2,000 surveillance cameras.