View the Surveillance Slide Show

When traveling to London, be sure to smile: the city is home to at least half of a million surveillance cameras—if you count video systems at banks, supermarkets and other commercial locations, according to The New York Times. And motorists with obnoxious vanity license plates, take heed: New York City has plans to install cameras that will snap a photo of every plate that enters the borough of Manhattan.

The range of human vocalization, from a full-throated bellow to a hushed whisper, typically lets you decide who will hear your voice. But what happens when that choice is taken away by technology that can pick up and transmit even the softest sounds? Add security cameras at gas stations, convenience marts, subway stops and street corners, and privacy appears to be little more than a quaint notion.

Some efforts to prevent the next terrorist attack have come at a cost to our privacy, whether through the government's expansion of its wiretapping and surveillance powers or an omnipresent network of cameras that scan our every move in the public square as we go about our daily lives.

Is this the cost of greater, and some would argue, necessary security? Or have governments and concerned parties crossed the line into prying and paranoia? Check out ScientificAmerican.com's in-depth report on privacy and security to learn more about these issues.

Here, see images of both conspicuous as well as not-so-noticeable surveillance devices, from the gas station closed-circuit camera to the telephone wiretapping equipment that has recently been the subject of political fights.

View the Surveillance Slide Show