Poststempel

Poststempel, or postmark, is a postal marking applied by a postal authority to a mail item, primarily to cancel the stamp and to record information about its processing. A typical postmark includes the date and place of mailing, and may also show routing information, a time, or a code. The mark prevents the stamp from being reused and provides a traceable record for transit and delivery.

There are two related concepts: cancellations, which physically deface the stamp to render it invalid, and postmarks, which may primarily convey date/place and sometimes accompany a separate cancellation.

History: Early mail services used handwritten or inked marks; in the 19th century, circular date stamps became standard in many countries; later, mechanical postmarking devices and metered mail expanded the formats.

Formats and shapes vary by country and era; common forms include circular date stamps, oval markers, and place-name with date in two lines; some postmarks show the town, province, or country; some are pure cancellations and do not show the date.

In philately, postmarks are studied as postal history; their legibility, town, and date influence the value; collectors categorize by place, era, and type; duplex or double postmarks combine cancellation and date.

Modern mail uses various systems: inkjet or printed date marks on the envelope or on the stamp; some mail uses non-stamp charges or meter marks that resemble postmarks.