Penny Black was world's first adhesive postage stamp. Britain issued the first adhesive postage stamp on 1st May 1840 and used as official on 6 May of same year (Although 6 May was the official date but postmasters started selling the stamps from 1 May). Before that wood was used for stamps. This invention also brings a new idea of pre-payment. Before 1840, the recipient of the mail has to pay for postage on delivery. The Penny Black allowed letters of up to 1/2 ounce (14 grams) to be delivered at a flat rate of one penny, regardless of distance in contrast to the existing system of paying postage on delivery, charged by the sheet and on distance travelled.
Mr. Rowland Hill idea reformed the British postal system and proposed an adhesive stamp to indicate prepayment of postage. The Postage stamp had the image of Queen Victoria, the word "POSTAGE" appeared at the top of the stamp and the total cost of the stamp was one penny which was indicated at the bottom of it. The postage stamp was printed in black ink by Perkins Bacon. Although the first adhesive postage stamp was used in Britain for the first time but the idea had at least been suggested earlier in Austria, Greece and Sweden. These Penny Black; stamps were cancelled by red ink, which was hard to see and easy to remove. This makes it possible to re-use stamps after they had been cancelled. In 1841 the Penny Red came into the market in place of Penny Black and cancellation was performed by black ink which was much more effective as as cancellation and harder to remove.
Together with Henry Cole, Mr. Rowland Hill announced a competition to design the new stamps. But no entry among some 2,600 entries was considered suitable. Instead a rough design by hill featuring profile of the former Princess Victoria was chosen because its an easily recognisable face. An envelope bearing a design created by the artist William Mulready was also issued.
Initially, size of postage stamps were supposed to be 3/4 inch square but to accommodate the writing at the bottom, the size was altered to 3/4 inch wide by 7/8 inch tall which is approx 19 x 22 mm. Revenue stamps had long been used in the UK and to distinguish postage stamps from revenue stamps, the word "POSTAGE" has been used at the top. Finely engraved engine turnings are in the background of the stamp. The sheets were printed by Perkins Bacon and consisted of 240 stamps in 20 rows of 12 columns. 240 pence or one pound is the cost of of one full sheet and one row of 12 stamps cost a shilling.