What Is Physical Security?
Physical security describes both measures that prevent or deter attackers from accessing a facility, resource, or information stored on physical media and guidance on how to design structures to resist various hostile acts. It can be as simple as a locked door or as elaborate as multiple layers of security systems.
Physical security, by no means, is a modern phenomenon. Physical security, as a field, exists in order to deter persons from entering a physical facility. Thus, as long as the need to defend physical facilities has existed, a need to provide for their security has also been needed. Historical examples of physical security include city walls, moats, booby traps, etc.
The key factor is the technology used for physical security has changed over time. While in past eras, there was no Passive Infrared (PIR) based technology, electronic access control systems, or Video Surveillance System (VSS) cameras, the essentially methodology of physical security has not altered over time.