A Hitchhiker is any item that moves from geocache to geocache. This item can be a fuzzy animal, a die-cast car, a coin, or anything else the originator could imagine.
The most common hitchhikers are travel bugs and geocoins trackable at Geocaching.com. However, there are other types of hitchhikers (including geocoins) that are trackable at other sites. Furthermore, hitchhikers do not need to be trackable at all: the most basic form is an item attached to a note that asks the finder to place it in another cache or to further some other goal.
According to the Geocoin FAQ and Travel Bug FAQ at Geocaching.com, the person who activates a hitchhiker remains its owner. Therefore, these hitchhikers are not considered trade items. They cannot be kept (because they remain the property of their owners, who released them to the wild), but they can be taken from a cache without leaving anything in exchange. Note that it is always acceptable to "trade up" by leaving a trade item when removing such a hitchhiker from a cache. Removing a hitchhiker does reduce the "interesting stuff" that the next person will find in the cache.
Other hitchhikers may be considered trade items. You are expected to trade fairly for such hitchhikers, and you then own them (until you give or trade them away).
Sites That Track Hitchhikers
- Geokrety (a non-commercial TB alternative)
- Geocoin.net (geocoin tracking)
- SigItem.com (signature item tracking)
- GPSgames.org treats hitchhikers the same as moving caches
There are also personal sites that track personal hitchhikers, such as Geofish.net (the digitalfish tracking site).