QSL Card from PK4XM (E. Marcks, Sumatra, East Indies) to W6DQZ (Hamid Durmisevich, Los Angeles, California), January 14, 1936

It was customary for ham radio operators (hams) to exchange these "QSL cards" with one another through the mail after their first conversation. Long-time hams amassed collections of thousands of cards, some from far-flung places. There is a story embedded in each example: the ham's call sign dominates the design, with additional details about location, reception reports, and weather conditions.