Cachet

In philately, a cachet is a picture or design, other than a cancellation or pre-printed postage on the envelope, postcard, postal card or other cover, that can be purely decorative, or commemorative. There are official and private cachets; they commemorate everything from the first flight on a particular route, to the Super Bowl. Cachets are also frequently made, either by private companies, or a government, for first day covers.

Cachets have been made by practically every method by which artwork can be made or reproduced. Cachets have been hand-painted, printed and computer-generated. Frequently flight cachets (which have also been used in space and on the moon) are rubber-stamped.