Decoding the Past: What Does "10-4" Mean?

What Does "10-4" Mean?

There have been countless codes, jargons, and phrases used by professionals to convey information quickly and efficiently. One such phrase that has found its way into popular culture is "10-4." You might have heard it in movies, TV shows, or even while listening to a police scanner. But what does "10-4" really mean, and how did it become such an integral part of communication history? 


We need to first understand the concept of " 10-codes". These codes are a system of abbreviations used primarily by law enforcement and emergency service personnel to facilitate quick and concise communication over the radio. They were developed to save time and reduce misunderstandings during radio transmissions.

The Origin and meaning of "10-4"

The " 10-4" code is part of a larger set of 10-codes, each with a specific meaning. The origins of these codes can be traced back to the 1930s when the Association of Public-Safety Communications Officials (APCO) began developing them. The "10" in "10-4" refers to the category of codes reserved for common operational and tactical phrases. The number "4" stands for the specific code.

When someone says "10-4" on a radio or during a conversation, they are essentially saying, "I understand" or "Message received." It is a way to quickly acknowledge that the information or instruction has been received and comprehended. 

The Popularity of "10-4"

"10-4" became widely recognized due to its prominent use in police procedural television shows and movies. The phrase's simple yet effective meaning made it a favorite among scriptwriters, and its adoption into popular culture was inevitable. It also gained popularity among citizens who listened to police scanners and wanted to understand the lingo.

Other 10-Codes

10-0   Use caution
10-1   Weak signal
10-2   Good signal
10-3   Stop transmitting
10-4   Affirmative (OK)
10-5   Relay to/from
10-6   Busy
10-7   Out of service
10-8   In service
10-9   Repeat
10-10   Negative
10-11   Animal problem
10-12   Stand by
10-13   Weather conditions
10-14   Message/Info
10-15   Civil disturbance
10-16   Domestic disturbance
10-17   Enroute
10-18   Urgent
10-19   Go to station
10-20   Location
10-21   Call _
10-22   Disregard
10-23   Arrived at scene
10-24   Assignment completed
10-25   Report to _
10-26   Detaining suspect
10-27   License info
10-28   Vehicle info
10-29   Records check
10-30   Unauthorized radio use
10-31   Crime in progress
10-32   Person with gun
10-33   Emergency

For more 10-Codes