Postmark

A postmark is a postal marking made on a letter, package, postcard or the like indicating the date and time that the item was delivered into the care of the postal service. Modern postmarks are often applied simultaneously with the cancellation or killer that marks the postage stamp(s) as having been used (though in some circumstances there may be a postmark without a killer, and sometimes the postmark and killer form a continuous design), and the two terms are often used interchangeably, if incorrectly. Postmarks may be applied by hand or by machines, using methods such as rollers or inkjets, while digital postmarks are a recent innovation. The local post Hawai'i Post had a rubber-stamp postmark, parts of which were hand-painted. At Hideaway Island, Vanuatu, the Underwater Post Office has an embossed postmark.

The first postmark (called the "Bishop Mark") was introduced by English Postmaster General Henry Bishop in 1661 and showed only the day and month of mailing in order to prevent the delay of the mail by carriers.

In England during the latter part of the 17th century several postmarks were devised for use with the London Penny Post, a postal system that delivered mailed items within the city of London. The postmarks bore the initial of the particular post office or handling house it was sent from along with a separate time stamp. Postage was prepaid and the postmark was applied to the mailed item by means of an inked hand-stamp. Some historians also consider these postmarks to be the world's first postage 'stamps'.

In the 19th century and early 1900s it was common for letters to receive multiple postmarks indicating the time, date, and location of each post office delivering or transporting the letter, and this is still occasionally true, though to a lesser extent (see "backstamp"). While almost every contemporary postmark includes a location as well as a date, in 2004 New Zealand Post announced plans to eliminate the location on their postmarks and include only the date; however, information about this can be determined by a three-number code on the postmarks.

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