Ten-codes, also known as ten signals, are brevity codes used by law enforcement and emergency services to communicate efficiently over radio transmissions. Each code begins with the number ten followed by another number, representing specific messages or instructions. For example, 10-4 means "acknowledged," while 10-20 refers to a location. These codes help reduce confusion and ensure clarity during critical situations. While ten-codes are widely used in the United States, their usage can vary by agency, and some organizations have moved towards plain language to enhance understanding among diverse responders.