Most people think about locks, bars, alarms, and uniformed guards when they think about security. While these countermeasures are by no means the only precautions that need to be considered when trying to secure an information system, they are a perfectly logical place to begin. Physical security is a vital part of any security plan and is fundamental to all security efforts–without it, information security, software security, user access security are considerably more difficult, if not impossible, to initiate. Physical security refers to the protection of building sites and equipment (and all information and software contained therein) from theft, vandalism, natural disaster, manmade catastrophes, and accidental damage (e.g., from electrical surges, extreme temperatures, and spilled coffee). It requires solid building construction, suitable emergency preparedness, reliable power supplies, adequate climate control, and appropriate protection from intruders.
References: Szuba, T. (1998). Safeguarding your technology: practical guidelines for electronic education information security. National Center for Education Statistics.