There are a few things that need to be cleared up in terms of terminology:
- Hits - this simply refers to the number of 'elements' loaded on your site. If one page has five images in it, viewing that page once adds 6 hits (one page + five images).
- Impressions - the number of times pages on your site are seen (also simply called pageviews). Impressions are sometimes referred to as 'hits' which can cause confusion.
- Unique visitors / Uniques - the number of people that visited your site.
So to clarify, if I visit your website, look at two pages, and each page has 5 images on it, then your stats increase by one unique, two page views, and 12 hits. Tracking on your site can be either done server-side or remotely. With server-side statistics, log files are used to generate visitor information. This is usually much more accurate than remotely hosted solutions. In such cases, you usually have to add some javascript to your site. This javascript is then used to track visitor data.
Our website hosting uses cPanel and so you can view visitor hit data. It also allows you to analyses your visitors with AWstats. However for best results we suggest using something like Google Analytics.
The main issue that you face when tracking visitors and usage of your website is that amongst all this data a lot of those impressions etc... are from Bots and spiders. Ie. they are not real people exploring your site. Which from a marketing and SEO perspective is problematic.
The raw visitor data is very much full of this which is why using a service like google analytics is probably the base strategy as there are a whole host of tools available and traffic from known bots and spiders is automatically filtered out (it doesn't catch everything though).