Errors, freaks, and oddities sound like judgmental characterizations, but for philatelists, these are terms of art. Errors are stamps with serious mistakes that are repeatable, for example, a missing perforation. Freaks are less serious defects, being stamps whose variations are minor. Oddities, not surprisingly, describe stamps that are neither errors or freaks, more like curiosities than out-and-out mistakes. For example, imperfect stamps produced solely to test whether they will dispense properly in vending machines are considered oddities.
Probably the most famous errors feature inverted images. For Australian stamp collectors, the prize is an Inverted Swan, a Western Australia stamp from 1854 whose frame surrounding the colony’s symbol, a black swan, is upside-down. The best known U.S. stamp error is the 1918, 24-cent Inverted Jenny. The stamp bore an image of a Curtiss JN-4 biplane, known as a Jenny, which flew the first scheduled air-mail routes in the United States. But one sheet of 100 stamps was printed upside-down, or, to put it more accurately, the sheet was fed into the press incorrectly, resulting in a stamp with an airplane on it that appeared to be flying upside down.
The error that produced the Inverted Jenny was undetected during printing, and while it affected a full sheet of stamps, it was not the sort of thing that needed to be corrected. Other errors, though, are spotted on stamps after they have been printed, and then steps are taken to nip the problem in the bud. For example, a red 1½-cent stamp issued in Fiji in 1938 featured the image of an outrigger canoe, its sails filled with a sweet tropical wind. But the artist who prepared the engraving neglected to put a sailor on board, so there was no one steering the ship. Once the oversight was discovered, the plate was re-engraved and the helmsman was added.
Spelling errors on stamps are easier to correct, such as the Cook Islands stamp from 1967 that depicted a water lily but identified it as a “Walter Lily.” More egregious is the Malawi stamp from 1965 that misidentified Lake Malawi as Lake Nyasa. And then there are errors that prove God is in the details, such as the 1956 East German stamp commemorating the life of 19th-century composer Robert Schumann, except the music originally placed as a background behind his green bust was by Franz Schubert.
Other compositional errors include placing landmarks from one region on stamps meant to depict another. In 1932, it must have been a surprise to Filipinos to learn that their Pagsanjan Falls looked exactly like Vernal Falls in California’s Yosemite National Park. Then there are examples of a printer’s laziness, such as the 1897 Newfoundland stamp that purports to show explorer John Cabot’s 15th-century ship, the Matthew, but instead reproduces Columbus’ Santa Maria from an 1893 U.S. stamp (both were printed by the American Bank Note Company).
In rare cases, errors are actually perpetuated, such as the 1962 Dag Hammarskjold four-cent stamp, whose inverted-yellow version was printed in relatively large numbers for the benefit of collectors before being corrected.