Many local areas use emergency population warnings to advise of prison escapes, abducted children, Emergency telephone number outages, and other events.

An emergency population warning is a method whereby local, regional, or national authorities can contact members of the public en masse to warn them of an impending emergency.

Early warning system is the term that the International Early Warning Programme coordinated by the United Nations uses for all systems that are used to send emergency population warnings.

The 'Common Alerting Protocol' (CAP) is an XML-based data format for exchanging Emergency population warning and emergencies between alerting technologies.