Signal devices are tools used to convey information or alerts through visual, auditory, or tactile means. Common examples include traffic lights, sirens, and flashing lights. These devices help ensure safety and communication in various environments, such as roads, emergency situations, and industrial settings. In addition to traditional signal devices, modern technology has introduced digital signals, such as LED displays and smartphone notifications. These advancements enhance the effectiveness of communication, allowing for quicker responses and improved awareness in both everyday life and critical situations.