A Geocoin is metal coin minted in similar fashion to a medallion, token coin or military challenge coin for exclusive use in the sport of Geocaching. A geocoin may be trackable on the internet using a serial number and website address engraved on the coin or untrackable.

Personal geocoins are a personal signature item bearing the geocacher's handle and personal design in a similar vein to a heraldic device. Geocoins are often minted by caching organizations and as fund raisers for geocaching events.

They may be placed in geocaches as signature items to be found by others and kept as trophies or moved from cache to cache like a Travel Bug, traded or given to other cachers like a calling card or merely sold and collected.

Trackable Geocaching.com geocoins are imprinted with unique codes and tracked via the geocaching.com website. An icon, sometimes unique, is shown on the geocaching website beside a cache the geocoin is in or in the inventory of any cacher holding one. Icons will also remain in the inventory of cachers who log the 'discovery' of a geocoin's number without physically removing it from a cache. Icon collecting is an associated hobby. Many people bring geocoins with unique icons to geocaching events so that others may see the coins and use the tracking number to collect the icons as part of their online statistics.