The first step is to request to send a postcard. The website will display, and send the member an e-mail with, the address of another Postcrosser and a Postcard ID (e.g.: US-787). The Postcard ID uniquely identifies that postcard in the system. The member then mails a postcard to that Postcrosser and writes the Postcard ID on it. The Postcrosser receives the postcard and registers it using the Postcard ID that is on the postcard. At this point, the member is eligible to receive a postcard from a different Postcrosser.