As I often come across postcard wishlists on postcrossers’ profiles where they are referred to by a country name or simply a number, I wonder if there is any widely circulated code list to facilitate cataloging and perhaps swapping. Meanwhile, I’ve started to compile one.
But before that, I’d like to know how many postcard series there are that are popular among postcrossers (say, relatively easily tradable domestically, regionally or globally)? Would appreciate it if you could reply and tell me some popular postcard series and their websites. Thank you!