What Is a CDV?

As I have been doing more research, I have been hearing the term 'CDV' a lot. I was reading an article to Mom when she voiced the question, "What is a CDV?" I didn't know.
So I looked it up. It is an abbreviation for carte de visite, which is a kind of picture that was patented by some Frenchman.
CDV's were the method the actual printing of the photo; each photo was very small, but most are incredibly clear. I know the one of the little girl's is rather blurry, but it was too cute not to post!