The "Ten-Code," also known as "ten signals," is a brevity code used in voice communication, particularly among law enforcement and emergency services. It consists of a series of codes that begin with the number ten, followed by another number, to convey specific messages quickly and efficiently. For example, 10-4 means "acknowledged," while 10-20 refers to a location. Originally developed in the 1930s, the Ten-Code helps reduce misunderstandings and improves communication in high-pressure situations. While it is widely used in the United States, some agencies have moved away from it in favor of plain language to enhance clarity, especially during emergencies involving multiple agencies.