The Global Positioning System (GPS) is what makes geocaching possible in the first place. GPS is a satellite-based navigational system developed by the military, beginning in the 1970’s. At first, the military didn’t want civilian users to have access to the most advanced and accurate GPS technology. That changed on May 2, 2000 when GPS technology was made available, for free, to the general public. The first geocache was placed, deep in a forest in Oregon, later that month, by a GPS enthusiast. He published the GPS coordinates on the web and encouraged folks to go find the container of goodies that he hid. And the rest, as they say, is history.
The following links provide some basic information about GPS technology: