What is it?
A souvenir is a virtual piece of art that is displayed in a user's profile at Geocaching.com, souvenirs are awarded based on criteria set by Geocaching HQ. Souvenirs are awarded for different things like attending specific events or logging caches at certain dates (E.g. Log a cache at International Geocaching Day.).
Top Souvenir Collectors is a top list of who has collected the most souvenirs.