Penny Black Stamp

The Penny Black was the world's first adhesive postage stamp of a public postal system. It was issued by the United Kingdom of Great Britain and Ireland on 1 May 1840, for use from 6 May of that year. Although all London post offices received official issues of the new stamps, other offices throughout the United Kingdom did not, instead continuing to accept postage payments in cash only for a period. Post offices in some localities, such as those in the city of Bath, began offering the stamp unofficially after 2 May.

Country of production : United Kingdom of Great Britain and Ireland
Location of production : London
Date of production : 1840
Nature of rarity : World's first postage stamp
Estimated existence : Unknown
Face value : 1-Penny
Estimated value : £3-4000 (mint)

Source: Wikipedia