> the usefullness of a GPS. And what is geocaching?

it's treasure hunt with this technical device, witch tells exactly where you are with coordinates, same as in good map. In that link we have mentioned it's explained more thruly. And there you can look for caches in the area you are going to visit.

Basics are 1. someone thinks that a place is worth to look for 2. He or she hides a small tupperware or film container or jam jar with a log book and pen and other 'treasures' in a good hiding place there and informs coordinates, nature, details and hints for finding it for example in http://www.geocaching.com 3. someone else seeks for caches from that same page and takes coordinates and other information from there 4. This other someone goes actually there and tries to find the container without anyone else noticing it. Also enjoys the views and buildings or what ever spectacular there is. 5. when found, This other someone logs name and date in the log book in container, leaves a small treasure and takes one, goes online when possible and in to the internet and logs the finding on the page of this cache. Treasures are like key rings, stickers, coins and stuff.

Hope this helps a bit and is not too much in this context. Kati, Kangasala, Finland