handles vs pointers

What is the difference between a handle and a pointer. I guess I always that that they were the same thing. But lately I have come to realize that they are not the same thing, at least not interchangable.

Is there some doc on this, or can someone please explain this to me?

int *ptr <-- pointer to int
int **ptr <--- pointer to pointer to int (handle)

so they are quite different...
guess that's it :)

/btq