A threat warning receiver is a device used to detect and alert of possible threats. Synonyms for such a device include radar detectors, warning systems, alert systems, early warning systems, alarm systems, and danger detectors. These are similar devices that perform the same task and are often used interchangeably. Other synonyms include defense systems, hazard alert systems, safety sensors, security devices, and emergency response systems. Some devices are designed for specific industries or purposes such as aviation or military threats. Regardless of the name or use, the purpose of all these devices is to provide warning and give individuals a chance to take action to protect themselves.