There are some things they won't move (cleaning liquids, for one), and obviously you'll want to remove anything particularly valuable, but otherwise, you point, they pack.

They will pack as much or as little as you ask them to do.

We have never used a full service moving company - packing, moving, etc. When a mover packs for you, how much do they pack? For example, are they taking literally everything and putting in a box. Or, do you have to do some level of pre-packing?