Overprints are postage stamps to which a text (and sometimes graphics) have been applied after their printing. Overprints have been used for several purposes, serving as rate surcharges, commemorations, control marks or the validation of stamps by a new postal administration. Precancels, also, are overprinted stamps.
Some overprints alter or confirm the face value of a stamp. These are commonly produced when some needed types of stamps are unavailable, whether because new shipments have been delayed, because circumstances have changed too quickly to get appropriate new stamps, or simply to use up existing stamps. Surcharging during the German hyperinflation of 1921-1923 is one such example. Many countries have used surcharges when converting to new currencies, for example many Commonwealth countries chose to convert to decimal currency in the late 1960s. Also, some incoming postal administrations have overprinted the stamps of an earlier administration to show the new administration's authority, as happened in Ireland in 1922.
Overprints have been used as commemoratives, as they are a lower-cost alternative to designing and issuing special stamps. The United States, which historically has issued very few overprints, did this in 1928 for issues commemorating Molly Pitcher and the discovery of Hawaii. Overprints applied by an entity other than an official stamp-issuing agency are called "private overprints."
A postal stationery envelope used from London to Düsseldorf in 1900, with additional postage stamp perfinned "C & S" identifying the user as "Churchill & Sim" per the seal on the reverse shown on inset. A perfin, the contraction of 'PERForated INitials', is a pattern of tiny holes punched through a postage stamp. Organizations used perforating machines to make perforations forming letters or designs in postage stamps with the purpose of preventing pilferage. It is often difficult to identify the originating uses of individual perfins because there are often no identifying features but when a perfin is affixed to a cover that has some user identifying feature, like a company name, address, or even a postmark or cancellation of a known town where the company had offices, this enhances the perfin.
Sir Rowland Hill (1795–1879) was a British teacher and pamphleteer who popularised the concept of penny postage at a rate of a penny per half ounce, without regard to distance. He is usually credited in the UK with originating the basic concepts of the modern postal service.
Hill published his famous pamphlet Post Office Reform: its Importance and Practicability in 1837 in which he called for postage to be prepaid by the sender. Hitherto postage had been paid by the recipient. He suggested the prepayment be proven by prepaid letter sheets or adhesive stamps.
In 1840 his proposals led to the introduction of the world's first postage stamp; the Penny Black.
... that the first Penny Post was established in London in 1680 by William Dockwra nearly 200 years before the better known Uniform Penny Post that was part of the postal reforms of 1839 and 1840 in Great Britain.
... that Czesław Słania (1921-2005) is the most prolific stamp engraver, with more than 1,000 post stamps for 28 postal administrations?
... that a forerunner is a postage stamp used during the time period before a region or territory issues stamps of its own?
... that the Royal Philatelic Society is the oldest philatelic society in the world, founded in London in 1869?
... that Marcophily is the specialised study and collection of postmarks, cancellations and postal markings applied by hand or machine on mail?
... that throughout U.S. history, different types of mail bags have been called mail pouch, mail sack, mail satchel, catcher pouch, mochila saddle mailbag, and portmanteau depending on form, function, place and time?
... that Non-denominated postage are postage stamps that do not show a monetary value on the face?
... that the Daguin machine was a cancelling machine first used in post offices in Paris in 1884?
... that the first airmail of the United States was a personal letter from George Washington carried on an aerial balloon flight from Philadelphia by Jean Pierre Blanchard?
The "Treskilling" Yellow, or 3 skilling banco error of color, is a postage stamp of Sweden, and as of 2004 the most valuable stamp in the world. To date no other example has been found, so is most likely the only one in existence.
The 3-skilling banco value of the first postage stamps of Sweden, issued in 1855, was normally printed in a blue-green color, while the 8-skilling was printed in a yellowish orange shade. In 1886, a young collector named Georg Wilhelm Baeckman was going through covers in his grandmother's attic, and came across one with a 3-skilling stamp printed in the yellowish orange shade of the 8-skilling.
Each time it has been sold it has set world records. In 1984 the stamp made headlines when it was sold by David Feldman for 977,500 Swiss francs. A 1990 sale realised over one million US dollars and in 1996 it sold again for 2,500,000 Swiss francs.