Denomination (postage stamp)

In 2007 the United States Postal Service issued its first undenominated "Forever stamp", which was guaranteed to remain valid for first-class postage despite any and all future postal rate increases.

[2][3] Sometimes a stamp may have its denomination changed by the post office due to local circumstances.

For instance, when the Ryukyu Islands (at the time a United States protectorate) changed its currency from Yen to Dollars, a number of airmail stamps originally printed with Yen values were overprinted and re-denominated to cents in 1959–1960.

During periods of hyperinflation, non-overprinted postage stamps of extraordinary denominations have been issued.

As one example, in Hungary, on 15 July 1946 an AP40,000 (Hungarian adópengő) stamp featuring a diesel locomotive[4] was issued.