For years I have seen three packs of cahier journals (Moleskine) and have wondered what they are, how they are used. What I mean is, they look like they can be fit into some sort of cover (mostly due to their plain appearance) and wonder how these are used. Are they stand-alone thin journals? Do they take well to fountain pen ink? I have used Moleskine and Piccadilly journals for years.

How are these journals typically used? Are they housed in a case?

I know this is a stupid question. I've been curious about this for years.