How are views calculated?

Apologies for the potentially very obvious answer, but thought it would be worth asking the community.

How are views determined? We use the Viewed Content report and sort by the number of views. Someone recently asked me if views are by unique users (I don't think so) or just by clicks (I believe this may be true). I'm confused by this Views definition:  Views Definition and the comments on this thread here: RE: Can you see the number of log ins on your community in reports? .

Do certain widgets have to be uploaded just to count views or is that only for unique views? I have a lot of questions! Thanks in advance.