I often hear people quote hits as a measurement of website traffic or popularity. This however can be a misleading statistic as many might not understand the difference between a hit a visitor or a view.
Here are a few brief descriptions of what these actually measure and why they might be used or misused at times.
Hits:
A hit is a request to a web server for a file, such as a web page, an image, a JavaScript file or a style sheet. As a web page can be made up of multiple files a single page view can equal many hits.
While hits are not a reliable method of website's popularity, this metric can be used to measure the amount of activity taking place on the server. This can be used to ensure that your server is capable of handling the anticipated load.
This is most useful to the systems administrator who would want to ensure that there are enough resources available on a server to ensure that the website operates optimally.
Views:
Views, page views or page impression is typically a request to load a single HTML file from a website. A page view is each time a visitor views a page on your website regardless of how many hits are generated.
Page view counts may also include hits on other files such as PDF documents, videos or Microsoft Office documents in addition to HTML files. This is useful when presenting information in various formats yet still wish to track usage.
This is a useful metric for those who might be interested in advertising on your website as it could reflect how many times their ad has been seen.
Visitors:
A visit happens when someone or something (robot such as Google Bot) visits your website. One visitor can make multiple visits to your website. From a marketing perspective, visitors are browser, or human, visits to the website where their "human" interaction with the website is recorded.
Unique visits or visitors are those reaching your website for the first time should they return, they add to the number of visits but are no longer considered a unique visitor.
This is a useful metric for marketers who might want to know how many people have reached the website to judge how successful their efforts have been in promoting a website.
As you can tell from the points above, it is important to know what you are tracking in order to accurately report a website's performance. Not all values are equal, but because they are tracking different things altogether. All values can be valuable depending on your objective. Once you've defined your objective it becomes a lot easier to understand what you need to track and why.