What is the meaning of the procedural signal “CQ”?

The procedural signal "CQ" is universally understood in amateur radio to mean "calling any station." It is an open invitation for anyone who hears the call to respond and initiate a contact. The term originated in early telegraphy, essentially sounding out the phrase "seek you." It is used across almost all modes, including voice, CW (Morse code), and digital, whenever an operator is looking for a general contact. While it is heavily used during contests, it does not stand for "Contest QSO" or "Communication Quality." It simply signals that you are on the air and ready to talk to whoever answers.