Hits:
A hit is recorded each time a file is accessed on your web server, whether it's an HTML document, a graphic, etc. Therefore, if your site has 9 graphics on a page, and including the html file, each visit to that page would equal 10 Hits. 1,000 visitors to such a page on your site equals 10,000 hits.

Page Views:
One visitor to a page on a site equals one page view. 1000 visitors to a page on a site equals 1000 page views.

Visitor:
A visitor is someone that visits your site. The visit can consist of one or more page views and/or hits. They are logged as as the same visitor no matter how many times they return to the site during a 24 hour period.

Summary:
The best way to measure your website traffic is with Page views. Page views represent the number of times the page was viewed, not an image.