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. Types of stamps include:

• Postage stamps, used on mail
• Revenue stamps, often used on documents; they are superficially similar to postage stamps, but may have very high denominations (see also Stamp Act and Stamp Duty)
• Rubber stamps, devices used to apply inked markings to objects