A “hit” DOES NOT actually refer to the number of times a user visits and/or clicks on a Web page. A “hit” refers to the user request for a Web Page “hitting” the web site’s server. Thus, you could have multiple “hits” to the server but only one view of the Web page. For example, if you have a page with 10 pictures, then a request to a server to view that page generates 11 hits (10 for the pictures, and one for the html file). A page view can contain hundreds of hits.
A page view is each time a visitor views a webpage on your site, irrespective of how many hits are generated.
A visitor counted only once in a specific time frame. So if someone visits the site today and tomorrow, they’re are counted as 1 unique visitor and 2 page views.
Google Analytics Blog does a good job of describing how to measure visitors accurately on Google Analytics.
The ultimate goal is to measure quality. One way to measure the quality of a site is a low bounce-rate or the visitors who move onto another site immediately after visiting your site. What does a high bounce rate tell you? Avinash Kaushik defines it as, “I came, I puked, I left.” So in other words a high bounce rate isn’t good.