The poster stamp was an advertising label, a little larger than most postage stamps, that originated in the mid-19th century and quickly became a collecting craze, growing in popularity until World War One and then declining by World War Two until they are now almost forgotten except by collectors of cinderella stamps.
The unofficial nature of poster stamps has led to debate about exactly what is and is not a poster stamp. One definition has been "labels without postage stamp values, not good for postal service; advertising labels or charity labels." 
The first poster stamps were inspired by the invention of the postage stamp. A perforated label was produced in England in 1864 to celebrate the 300th anniversary of Shakespeare's birth and in Italy a label was produced in 1860 to celebrate Garibaldi's expedition to Sicily during the campaign to unify Italy. Commercial interests soon realised the publicity potential of the stamps and they were quickly adopted for the promotion of every type of product and cause. Poster stamps were also widely used by both sides during World War One as political propaganda.
As late as the 1930s they were still being used to promote political and other causes. In 1937 Irene Harand published a series of anti-Nazi poster stamps portraying the contributions made by Jews to civilisation over the centuries, and adhesive labels of all kinds that are not postage stamps continue to be produced today to promote particular causes or events.
- Patrick, Douglas & Mary. The Hodder Stamp Dictionary. London: Hodder & Stoughton, 1973, p.191. ISBN 0-340-17183-9
- Mackay, James. The Complete Guide to Stamps and Stamp Collecting. London: Hermes House, 2005, p.62. ISBN 1-84477-726-X
- Rogers, Peter. "Irene Harand and The Truth About Anti-Semitism." in The Cinderella Philatelist. Vol.48, No.3, July 2008, p.124.
- Blase, Ch. J. Hungarian Poster Stamps and Similar Cinderellas: A narrative and illustrated catalogue. Alton: World Poster Stamps, 2000. ISBN 1-901959-25-2
- Kiddle, Charles. Ludwig Hohlwein: The poster stamps. Alton: World Poster Stamps, 1999. ISBN 1-901959-15-5
- Schmidt, Walter., ed. "The Poster Stamp Report" in The Cinderella Philatelist, Journal of The Cinderella Stamp Club. ISSN 0009-6911
- Steele, H. Thomas. Lick 'em, Stick 'em; the Lost Art of Poster Stamps. New York: Abbeville Press, 1989. ISBN 0-89659-899-3
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