The Origin: Penny Black 1840 - Plate 1 (NG) - Certified by Richard Borek

The Penny Black was the world's first adhesive postage stamp used in a public postal system. It first was issued in Great Britain on 1 May 1840, for official use from 6 May of that year. It features a profile of Queen Victoria.

In 1837, British postal rates were high, complex, and anomalous. To simplify matters, Sir Rowland Hill proposed an adhesive stamp to indicate pre-payment of postage. At the time it was normal for the recipient to pay postage on delivery, charged by the sheet, and on distance traveled. By contrast, the Penny Black allowed letters of up to half an ounce (14g) to be delivered at a flat rate of one penny, regardless of distance.

Source : Wikipedia