Sending and receiving snail mail may be a thing of the past, but receiving a handwritten letter in today's constantly connected society is arguably just as joyous and unexpected as it was hundreds of years ago.
Take a journey back in time and check out five pieces of 19th-century history: These are the most valuable—and expensive—postage stamps out there.
5. Baden 9 Kreuzer
Value: $1.55 million
Why: Originally meant to be pink, an error occurred and several sheets were printed green. Three cancelled copies and one unused copy have been discovered.
4. Sweden Three-Skilling Banco
Value: $2.3 million
Why: Each stamp value series was a different color; however, an error caused a three-skilling stamp to be printed on the yellowish-orange paper that was intended for the eight-skilling denomination.
3. The Two Penny Blue
Country: United Kingdom of Great Britain and Ireland
Value: $4 million
Why: It's considered the world's second official postage stamp and rarer than its predecessor, the Penny Black.
2. Penny Black
Country: Great Britain
Value: $5 million
Why: Proposed by Sir Rowland Hill, this stamp depicting Queen Victoria is said to be first adhesive postage stamp in the world.
1. British Guiana One Cent Black on Magenta
Country: British Guiana
Value: $9 million
Why: This stamp features the colony's Latin motto: Damus Petimus Que Vicissim, which means We Give and Expect in Return. There is only one known copy, which was used on local newspapers.