[DensetsuNoKaboom]

What I know is:

Dummy objects are important. You can't see them (unless you look at my world below) and they don't generally do anything by themselves. However, you can drop them at the camera or any other object in the world, without using up space on a whole new object. Then, if you move the object, and want it to move to exactly where it was, you can tell the object to "set point of view to" the dummy. With the "<object> set point of view to" method, you can also do this while the world is running. They are quite useful.

As I said before, it's generally impossible to see them, however, a world I am attaching shows my little brother's discovery of how to make the invisible visible. It also uses a dummy for the normal purpose.