Here is a description of Geocaching from Wikipedia.
Geocaching, is an outdoor treasure-hunting game in which participants (called "geocachers") use a Global Positioning System receiver or other navigational techniques to hide and seek containers (called "geocaches" or "caches") anywhere in the world. A typical cache (pronounced /kæʃ/ like the English word cash) is a small waterproof container containing a logbook and "treasure" (usually toys or trinkets of little monetary value).
For the traditional geocache, a geocacher will place a waterproof container, containing a log book (with pen or pencil) and treasures, then note the cache's coordinates. These coordinates, along with other details of the location, are posted on a website (see Websites for geocaching). Other geocachers obtain the coordinates from the Internet and, using handheld GPS receivers, seek out the cache. The finding geocachers record their exploits in the logbook and online. Geocachers are free to take objects from the cache in exchange for leaving something of similar or higher value, so there is treasure for the next person to find.
Typical cache treasures aren't high in intrinsic value. Aside from the logbook, common cache contents are unusual coins or currency such as two dollar bills in the United States, small toys, ornamental buttons, CDs or books. Also common are objects that are moved from cache to cache, such as Travel Bugs or Geocoins), whose travels may be logged and followed online. Occasionally, higher value items are included in geocaches, normally reserved for the "first finder", or those locations which are harder to reach.
Geocaches can range in size from "microcaches", too small to hold anything more than a tiny paper log, to those placed in five-gallon buckets or even larger containers.
If a geocache has been vandalized or stolen, it is said to have been "muggled" or "plundered". The former term plays off the fact that those not familiar with geocaching are called "geo-muggles" or just muggles, a term borrowed from the Harry Potter series of books. If a cacher discovers that a cache has been muggled, he or she can flag the cache as needing maintenance, which sends an e-mail to the cache owner so it can either be repaired, replaced or deactivated.
Geocachers who have done the sport for awhile often recognize small things out of place that the muggle will never see, and find a geocache there even without their GPS. Geocaching is something that can take practice for the more inventive geocaches.
My home teacher, S to the Dowler, came over with his wife and ate our food. He brought with him a sweet hand held GPS device to take us on a quick geocaching adventure. The cache was stashed a week ago, so it was new to S to the D and us. We gladly accepted his offer. The cache was in our town center which is only a five minute walk from our home. His GPS system can get a cacher within 9 feet of the object at best. Once we were with in the twenty foot range we were on our own to find the prize. Leave it to my wife to find the sweet thing.
The reason I call it the exercise of nerds is because a cache could be exiled to a far off trail miles from any road. In essence, it is a global scavenger hunt for dweeb. Publicly I act not interested in such activities, but deep down I am a closet nerd yearning to go cache hunting again. Must have more!!!!!!!!