What is the purpose of a transponder in aviation?

The purpose of a transponder in aviation is to emit a unique code that can be detected by air traffic control (ATC) radar systems. This code, known as a squawk code, identifies the aircraft on radar and provides vital information regarding its altitude, helping ATC monitor traffic and maintain safe separation between aircraft. Transponders enhance situational awareness for both ATC and other aircraft in the vicinity.

While there are other systems in an aircraft that monitor engine performance or facilitate navigation and communication, these do not relate specifically to the transponder's function. The transponder primarily focuses on enhancing visibility and safety in the airspace by transmitting information back to ATC, making it an essential part of modern aviation operations.