Physical security is humanity’s oldest form of access control. Chances are good that you encounter many types of physical security every day, without really thinking about what they are and why they are there. As a security practitioner, it is important that you understand the purpose behind physical security measures and how they contribute to an overall access control strategy.

A good physical security strategy is designed in layers. This ensures that if an intruder bypasses or breaks through one layer, another layer will delay or stop him or her. In this section, you will read about the various layers that comprise a physical security strategy.