Security guard services provide and perform entrance and exit screening, personal and property security, emergency rescue and emergency management services, security patrols, and system monitoring. They may be armed or unarmed, stationary or mobile, and uniformed or non-uniformed. Security guard services are staffed by trained personnel who provide security services that cannot be managed by other systems. Some safeguard groups and individuals at bus or train stations, airports, sports stadiums, shopping malls, and other public places. Others protect persons and property at commercial buildings and industrial facilities. For example, security guard services may provide personal protection to corporate executives or safeguard expensive machinery.