The Stamp reference article from the English Wikipedia on 24-Jul-2004
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Stamp

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A stamp is a distinctive mark or impression made upon an object, for instance those made on a piece of paper and used to indicate the prepayment of a fee or tax.

The postage stamp is the most familiar type of stamp.

Revenue stamps are often used on documents; they are superficially similar to postage stamps, but may have very high denominations.

See also: Stamp Act