Papillon, Phalene, Dog Overbite vs Underbite

You may have a Papillon, or other (small) dog with an incorrect bite, but you are not sure whether it is over-, under-, or what not bite.
So, let us clarify this, for you to know at least what problem bite your pet has.

 Correct bite:

Severe overbite:

Severe underbite:

All images where taken from Google search.