Postage stamp prepaying. From when the first postage stamps were used, postmarks were applied to prevent the stamps being used again. The first stamp, the "Penny black", became available for purchase 1 May 1840, to be valid as of 6 May 1840. Two days later, 8 May 1840, the Two penny blue was introduced. The Penny black was sufficient for a letter less than half an ounce to be sent anywhere within the UK. Both stamps included an engraving of the young Queen Victoria, without perforations, as the first stamps were separated from their sheets by cutting them with scissors. The first
Denomination (postage stamp) existing denominations became worthless. In other cases, changes to the local currency have led to changes in denomination. 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 a AP40,000 (Hungarian adópengő) stamp featuring a diesel locomotive was issued. This was the equivalent of 80 quadrillion pengő (P80,000,000,000,000,000,000,000,000) Denomination (postage