Until 1840,there was no such thing as a postage stamp. If you wanted to mail a letter. you brought it to the post office and paid the postmaster the proper amount. If there was a crowd, you stood and waited.
Then in 1840 in England, a man named Rowland Hill had an amazing idea. He thought that if poeple had stamps to stick on their envelops, they wouldn't have to go to the trouble of visiting the postmaster for each letter they wanted to send. The idea was accepted in england. and the first stamps were made, with picture of queen victoria on each.
The convenience of postage stamps appealed to people, and soon the idea caught on Now almost every country in the world makes stamps for licking and sticking. Stamps also introduced the hobby of stamp collecting - something that Hill never even thought about it.