Yes. Can I attach a stamp (supplementary stamp) to an envelope myself that has already been franked with WebStamp (old face value) and post it in a letter box? a b Garfield, Simon (2009). The Error World: An Affair with Stamps. Boston: Houghton Mifflin Harcourt. p.118. ISBN 978-0-15-101396-8.

United States Postal Service / Airmail". Archived from the original on 23 June 2011 . Retrieved 31 July 2010. Glossary of Terms". American Philatelic Society. 2017. Archived from the original on 7 April 2017 . Retrieved 7 July 2017. As postage stamps with their engraved imagery began to appear on a widespread basis, historians and collectors began to take notice. [29] The study of postage stamps and their use is referred to as philately. Stamp collecting can be both a hobby and a form of historical study and reference, as government-issued postage stamps and their mailing systems have always been involved with the history of nations. [30] [31] First round United States postage stamp on the way, and that's not all..." Seattle Post-Intelligencer. Associated Press. 14 June 2000 . Retrieved 22 January 2011.Once again, a mistake has turned an otherwise normal stamp into one of the most valuable stamps. Made to commemorate the Chinese Cultural Revolution, this stamp includes a worker, farmer, and soldier all carrying a copy of the Selected Works of Chairman Mao.

The Universal Postal Union, established in 1874, prescribed that nations shall only issue postage stamps according to the quantity of real use, and no living persons shall be taken as subjects. The latter rule lost its significance after World War I. [37] The twentieth and twenty-first century [ edit ] The US Mail postage stamp of Marshal C. G. E. Mannerheim from 1961XLS file for Priority Mail Express International – Retail | CSV file for Priority Mail Express International – Retail Whatever the case, the most valuable stamps in the world are sure to continue their climb in value as the years pass. Make sure you keep your tongue off of them! 21 most valuable stamps in the world