Consolidated pageviews: Logged in users vs Anonymous in a "private" community

King of n00b questions here, with yet another.

In my admin’s dash, I can see Consolidated pageviews. For each day, there are numbers for logged in users, anonymous users, and web crawlers.

My community is currently set to private access (forum can only be accessed by a logged in user who has had an administrator-approved account).

My question:

What exactly is an anonymous user, and what constitutes a pageview?

People who visit the login page see not logged in, so they are anonymous.