A security guard (or security officer) is a person who is paid to protect property, assets, or people. Security guards are usually privately and formally employed personnel. Often, security officers are uniformed and act to protect property by maintaining a high visibility presence to deter illegal and inappropriate actions, observing (either directly, through patrols, or by watching alarm systems or video cameras) for signs of crime, fire or disorder; then taking action and reporting any incidents to their client and emergency services as appropriate. Until recently, the term watchman was more commonly applied to this function, a usage dating back to at least the Middle Ages in Europe. This term was carried over to North America where it was interchangeable with night-watchman until both terms were replaced with the modern security-based titles. Security guards are sometimes regarded as fulfilling a private policing function.
Contributions by Exit2DOS2000, Captain Jason, and Necrothesp.