"10-Codes," also known as ten signals, are brevity codes used in voice communication, particularly by law enforcement and emergency services. These codes help convey information quickly and clearly, reducing the chance of misunderstanding. Each code begins with the number 10, followed by a specific word or phrase that represents a particular message, such as "10-4" for acknowledgment. Originally developed in the 1930s, 10-Codes have been widely adopted across various agencies in the United States. However, their use has declined in favor of plain language communication, especially in multi-agency operations, to ensure clarity among all responders.