Postcrossing is an international postcard exchange project. It was set up on July 13, 2005 by Paulo Magalhães from Portugal. Postcrossing has since become an exchange project with over 671,000 users (March 2017) from 207 different countries. In February 2017, the 40,000,000 postcard sent by postcrossing was received.
How does it work?
After someone has created an account on the Postcrossing website, he can request an address for sending a postcard as a participant. When requesting an address, he also receives a Postcard ID. This is a two-letter code (the country code, for example, in the Netherlands, for example, NL) and a few digits. This code must be written on the card so that the recipient can register the card. When a card is registered, another person receives the sender's address, giving each participant one card for each card he sends.