Google has created a Google Doodle to honour 175 years since the introduction of the Penny Black stamp.
The Penny Black was the world's first adhesive postage stamp designed for use in a public postal system, and was issued on 1 May 1840. The 19 x 22mm design featured a profile of Queen Victoria aged 15.
The Penny Black is among the most sought-after in the world for stamp collectors, despite the fact mass production means many examples have survived. Depending on its condition, a Penny Black today could be worth anything between £1,800 - £15,000.
A block of 18 mint condition Penny Blacks were valued between £200,000 and £250,000 in 2007.
Ryan Germick, Google's Doodle team leader, recently said that each Google Doodle takes around a week to develop, while some more intensive projects can take months.