Ten-four is a popular radio code used by police officers, truck drivers, and other emergency response personnel to confirm receipt of a message or to indicate that everything is okay. The term originated in the United States and Canada and is now commonly used throughout the world. There are many synonyms for ten-four that can be used to indicate the same message, including "roger that," "copy that," "affirmative," "acknowledged," and "10-4 good buddy." While the exact phrase used may vary depending on the context and the specific group using it, the meaning of the message remains the same: the person receiving it is letting the sender know that they have heard and understood their message.