Did You See Th at! (Observation)
Introduction Observation is the central principle of security. It is both a deterrent and a detector. It is a deterrent because people are less likely to do something illicit if they believe someone will see them doing it, and it is a detector when an illicit act is seen. Observation is not limited to sight; it can be a function of any of the ﬁ ve senses or any number of mechanical or technological sensors. A magnetic switch on a door observes (senses) when the door is opened or closed; a motion detector observes something moving through a space and so on.