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

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

For more 10-Codes