Geocaching started in the United States in the year 2000 when the US military switched off selective availability of the GPS system. For civilians using a hand held GPS device instead of being accurate to about 100m, civilian GPS receivers were now accurate to less than 5m. Pretty good odds for finding that "box in the bush".
Geocaches can be as large as 20 litre bucket (or bigger) or as small as the nail on your little finger. Geocaches can be found in the bush, up a mountain, in a suburban park, in the middle of a busy city, anywhere where there is space to hide something and its publically accessible. The thing that they all have in common is that all have something for you to write your name on as a way of saying I was here on this date and I found it!.
All you need is a GPS or a Geocaching App for your smart phone and a sense of adventure; and maybe a pen or pencil - so you can sign the log.
For Australian there are two main websites promoting Geocaching and providing details on how to find caches.
Geocaching.com This is the original geocaching listing service. They have the details of over 2,000,000 million caches worldwide. This site is sometimes referred to as gc.com but that's not its proper address.
Geocaching Australia. This is the Australian listing service. The rules are more flexible and they have different kinds of caches - eg caches you can move around, virtual and history caches where there is no logbook but you have to answer some questions to prove you visited the site. This site is often referred to as GCA.
So what is a travel bug? Travel bugs (TB) are little metal tags with a unique number etched on the back. These get attached to something - a unique key tag, a old piece of computer, even a 'toy'. Generally these are left in geocaches for others to find but you don't keep these, the idea is that you leave them in another cache so they get to move around. Some travel bugs can have a specific goal - eg to be left in caches near the sea, or to visit skate parks. Other goals could be to start at one place and travel to somewhere specific - eg start at a little country AFL ground and eventually end up as close to the MCG (Melbourne Cricket Ground where the AFL Grand Final is played). Of course, you don't have to drive from 'upper woop woop' to Melbourne yourself, you might just leave it in a cache in the next town, then someone else will pick it up and move it a little further.
But Samboo is too big to be a travelling travel bug. Instead he is just a discoverable and visiting Travel Bug. This means that he stays with us and is not left in any caches. When we (and that includes Samboo) find a cache, we will register that he has Visited that cache. At events when geocachers get together socially, he wears his special TB tag which means that other geocachers can Discover him - ie note his unique number and write on his page the fact that they have met him. When he goes to events, Samboo usually brings his special book which has his story. He has met many new friends at events.