Apostage stamp is a small piece of paper that is purchased and displayed on an item of mail as evidence of payment of postage.
A couple days ago, I was looking for some images at Wikimedia Commons and accidentally found some old stamps from various countries and they totally blew me away, especially the triangular postage stamp. I just kept digging and later on I decided to write an issue about old stamps on LessThan100g. During the process I also found the first modern postage stamp - Penny Black, which is first stamp I put on the page (top left), it was released on May 6, 1840. Queen Victoria's head was engraved on the Penny Black, and she remained on all British stamps for the next sixty years. Rowland Hill created the first stamp. If you are interested in the history of these old stamps and would like to explore more, check out the Postage Stamp article on the wiki.