Signal devices are tools used to convey information or alerts through visual, auditory, or tactile means. Common examples include traffic lights, whistles, and flashing lights. These devices help communicate important messages, such as stopping or proceeding, to ensure safety and coordination in various environments. In emergency situations, signal devices like flares and alarm sirens play a crucial role in alerting people to danger. They can be used in different settings, including vehicles, aircraft, and maritime operations, to enhance communication and response efforts. Proper use of these devices can significantly improve safety and awareness.