“Geocaching was invented in May 2000, within days of the US Government switching off the security restrictions on global positioning systems that limited the accuracy of civilian receivers. A Portland computer consultant, Dave Ulmer, posted a message online that he had hidden a plastic bucket with software, videos, books, food, money and a slingshot in the woods near Portland, says the author of Geocaching For Dummies, Joel McNamara. “He used his GPS receiver to record the latitude and longitude and encouraged others to try to find it,” McNamara says.”