USAAF unit identification aircraft markings

USAAF unit identification aircraft markings, commonly called "tail markings" after their most frequent location, were numbers, letters, geometric symbols, and colors painted onto the tails (vertical stabilizer fins, rudders and horizontal surfaces), wings, or fuselages of the aircraft of the United States Army Air Forces (USAAF) during the Second World War. Tail codes and markings provided a visual means of identification in conjunction with the call procedures, and later assembly and combat visual identification of units and aircraft.

Source: Wikipedia — USAAF unit identification aircraft markings (CC BY-SA 4.0)