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Poster stamps were an extremely popular advertising medium until approximately the middle of the 20th century. Attached to the envelope in addition to the normal current postage stamp of the time they would serve all the same purposes as a specially designed commemorative postage stamp—advertising and promoting specific events. Some of the most common themes appearing on poster stamps were expositions and sporting events—particularly the Olympic games. Germany was one of the most prolific producers due to the lead held in printing technologies during these times. The poster stamp illustrated was issued to promote the German Health Exhibition in 1914 and depicts a stylised heart and systemic and pulmonary circulations. Due to their vivid designs and colours poster stamps were once very popular collectible items and nowadays, to a large extent, replaced by true stamps in the form of commemorative issues.