I have been Geocaching since 2008. It's a great way to get out of the house and I have used it many times to give me a new destination when I couldn’t think of one to go to. I get an area that I have not cached yet and go out caching (verb: to collect geocaches) somewhere new.
There are a couple types of Geocaches: Traditional, Multi-Traditional, Virtual, Earth Cache, Mystery and NGS Benchmarks, and is measured between 1-5 stars in difficulty and terrain. Difficulty is measured based how hard it is going to be to find it based on either size, camouflaged style and so on, and terrain is measured based on how hard it will be to get to the cache. For example, if you have large basic ammo box (these are some of the best by the way because they have all kinds of stuff in them), but it’s on the edge of a cliff, you would expect 1.5 Star Difficulty and 4 star Terrain. Here is a video that gives a nice summery of Geocaching and what to expect.
Once you get started you will earn various achievements such as Souvenirs. Souvenirs are virtual pieces of art that can be discovered. Along your travels you will find Trackables in caches; Trackables are pieces that have a mission. You can get Trackables of your own and give them custom missions, or help others achieve their mission. The Souvenir below is for Leap Day 2016 and my favorite Souvenir I have achieved. It is only obtainable by caching on February 29th during a Leap Year.