A little home for your dog within your home. It helps them feel secure and that they have a space that is their own.
So, a kennel? Forgive me, I am not a dog person, though I quite like my cleaning ladys little doggie.
Some dogs love them for their feeling of security, some dogs hate them because they feel confined.
My dog loves his for security; we always leave it open and whenever he feels stressed out he'll go in there for a bit to recharge. We have a blanket over the top and sides with the crate under the stairs so it feels like a cave to him!