Geocaching is more than using million dollar satalites to find tupperwear in the woods. You can also find trackable items inside of geocaches, at events, or pass them from person to person. They can be collected and shared with friends or released into the wild to be discovered. Oftentimes they have a goal to achieve, so help them on their way and remember to correctly log them so that you and others can see their progress as the travel, often around the world.
Travel bugs (dog tags), geocoins, and other trackable items will have an alphanumeric identification written or engraved on them. Write down this code and visit the trackables home site (http://www.geocaching.com/track/default.aspx). Type this code into the search bar "Enter the Tracking Code of the Item:" and press "Track." This will take you to the home page of that specific trackable and then you will log your find just like you would a geocache. The options for your find will be different. You can "retrive" it from the cache or owner if you wish to take it on an adventure with you. Take a photo if you want as well. If you don't want to take it with you, "discover" it. Once again, when you log your find, you will need the tracking number.
Be aware of the goal for the trackable. If you are unable or unwilling to help it along its intended goal then reconsider taking the trackable and discover it instead. Sometimes the goal may be a race. These can be a race against other bugs to visit the most destinaions, travel the furthest, or even take the most photos. Helping out is fun and can add to your adventure down the caching road.
https://www.geocaching.com/track/howto.aspx
https://www.geocaching.com/track/travelbugfaq.aspx