A cache that you find on the computer
A cache that is visible on google earth
A cache that doesn't have a physical object, instead you visit a location.
A cache that can be moved around
Take some swag (and replace it with an item of equal or greater value)
Sign the log book
Put some food to keep the next hungry cacher going.
Take some swag and walk away
Take the cache home with you
Replace the container in it's original place after you're done with it
Put the container back several meters from where you found it, to keep adding a challenge.
You can give as many as you like!
Both are allowed!
Neither are allowed!