Web Analytics Definitions
Hits
A request for a file from the web server. The number of hits received by a website is frequently cited to assert its popularity, but this number is extremely misleading and dramatically over-estimates popularity. A single web-page typically consists of multiple (often dozens) of discrete files, each of which is counted as a hit as the page is downloaded, so the number of hits is really an arbitrary number more reflective of the complexity of individual pages on the website than the website's actual popularity. The total number of visitors or page views provides a more realistic and accurate assessment of popularity.
Visits
A series of requests from the same uniquely identified client with a set timeout. A visit is expected to contain multiple hits and page views.
Unique Visitors
The uniquely identified client generating requests on the web server or viewing pages within a defined time period. (30 minutes for Caorda Analytics)
Single Visit Visitors
A unique visitor that is making their first visit.
Repeat Visitors
A unique visitor that has made at least one previous visit.
Page Views
A request for a file whose type is defined as a page in log analysis. A single page view may generate multiple hits as all the resources required to view the page (images, .js and .css files) are also requested from the web server.
SOURCE:
wikipedia