Physical security is often the first concern in facilities with high asset concentration, especially that used in critical systems for business processes. Physical security is especially important for IT resources, as their proper operation demands that the hardware assets and infrastructure they are running on be kept away from anything that could hinder their function. This includes tampering by unauthorized personnel and unforeseen events like accidents and natural disasters.

There are two phases of physical security:

• Deterrence: Methods and measures that are meant to deter attackers and intruders or prevent natural events and accidents from affecting protected assets. The simple method for this is through the use of physical barriers and signs. The signs serve as a warning to any intruder that their actions will bring physical harm or prosecution. The physical barriers are meant to prevent access entirely or simply to provide protection from external factors like storms or vehicular accidents.
• Detection: Allows security personnel to detect and locate potential intruders using surveillance equipment like cameras, motion sensors, security lights and personnel like security guards and watch dogs.