Radiographer......please share with us lesser mortals....what is geocaching?

Hmmmm....let's see....."caching" is the sound of a cash register, and "geo" has to do with the earth, soooo....
"geocaching" = a paleolithic cash register (Flintstones?); or
= a cash register imbedded in solid rock (prevents snatch & grab)
= a "geo"stationary cash register in orbit over the equator.

And to think you've several right on your route...wow!