The device makes use of infrared light rays to image radiation that is coming from a person’s body. If the person is carrying a metal object such as a gun, it will prevent the rays from reaching the part of the body where the object is. This will result in the appearance of an outline of that object on the scanner.
If you follow politics at all you have likely heard about the Occupy Wall Street Movement. Essentially, the movement is about protesting social and economic inequality, corporate greed, corruption, and influence over the government by rich corporations.