170 years ago the world's first adhesive stamp, the Penny Black, was introduced in Britain by the famous reformer, Rowland Hill.
It was issued by the United Kingdom of Great Britain and Ireland on 1 May, 1840, for use from 6 May of that year.
Penny Black's impact on society was remarkable. Despite the Penny Black stamp is not a rare item, it has totally changed the world, making a revolution in the communication systems.
By the end of 1840, more than 160m letters had been sent, doubling the previous year's figure. By the turn of the century, the figure had rocketed to 2.3 billion.
People started to collect stamps almost straight away, most notably John Edward Gray who bought penny black stamps on their first day of issue in order to keep them. Children and teenagers were early collectors of stamps in the 1860s and 1870s. Many adults dismissed it as a childish pursuit but later many of those same collectors, as adults, began to systematically study the available postage stamps and publish books about them.
Today, stamp collecting is one of the world's most popular indoor hobbies.
Famous stamp collectors
Freddie Mercury, lead singer of the band Queen, collected stamps as a child. His childhood stamp album is in the collection of the British Postal Museum & Archive.
John Lennon of The Beatles was also a childhood stamp collector. His stamp album is held by the National Postal Museum.
Star women's tennis player Maria Sharapova has been an enthusiastic collector of stamps since a young age.
England's King George V reportedly possessed one of the largest stamp collections in the world and became President of the Royal Philatelic Society at one point.
This collection was passed on to Queen Elizabeth II who, while not a serious philatelist, has a collection of British and Commonwealth First Day Covers which she started in 1952.
U.S. President Franklin Roosevelt was an avid stamp collector who designed several American commemorative stamps while president.