A Page View is literally an instance of a visitor loading a particular web page from your site. For example, if someone visits your homepage, we count a page view for that page.
A Click is a term generally used in connection with campaigns because the most important information is - how many times did a particular campaign ad bring a visitor to my site?
For example, say you have set up a banner campaign which will bring visitors to a particular page within your site. We will count the number of times that banner referred a visitor to your site - i.e. the number of clicks on that banner.
A Visit denotes one continuous visit to your web site. When a visitor first loads a page from your web site, a unique visit ID is created to track that visitor’s activity. The visit ends after 30 minutes of inactivity.
If a visitor visits your website and clicks around to see a few pages, and then leaves to go to another site, this is one visit and the visitor has terminated the visit himself. However, sometimes a visitor will open a page on your site and leave it open while he goes to walk the dog or make some coffee. If the visitor leaves a page open for 30 minutes without clicking further or doing anything on that page, we will assume that the visit is over. If after 30 minutes, the visitor comes back and begins to surf again, we will count this as a new visit.
A Visitor is the person visiting your website. It is important to remember to not mix up the figures for Visitor and Visit. For example, if a person visits your site once in the morning and once in the evening - in your report for the day, you will see one Visitor and two Visits, assuming that the visitor has not deleted their cookies.