The Guernsey issue stamp, depicts an outline of Guernsey with a smiley face, giving the ‘thumbs up’ to the hobby of Postcrossing.

Postcrossing is the union of the words "postcard" and "crossing" and its origin is loosely-based on the Bookcrossing site (with postcards, instead of books). However, the "crossing" or exchange of postcards works in a different way. Members send postcards to random members of the project, and in turn receive postcards back from other random postcrossers. This means that members cannot choose where their next postcard is going to and likewise, they don’t know where their incoming postcards come from, thus ensuring the element of surprise when one opens their mailbox. Exchanges are always unique and never more than once between the same members. The project is completely free and anyone with an address can create an account. However, the postcards themselves and postage fees to mail them are the responsibility of each user.

In April 2014, Postcrossing has over 470,000 members in 218 different countries who had registered and exchanged over 23 million postcards that have traveled almost 118 billion kilometers.