Not knowing what country or city you are located in can limit the answers you receive. In general terms a "security patrol service" is one where a "security guard" a human being actually views and or physically "checks" the security of a business, residence or person. Another variation is one where a security alarm system is activated and the monitoring station sends a security guard to verify the alarm. It is the responding guard who would then call the local authorities. Those are the basics. Various countries have different variations of the service.
