Web Site Statistics/Analytics
Being able to see the visitor statistics is a key point in being able to effectively track your marketing campaign. 
Search Term statistics will identify what you are ranking on and will give you an idea of whether you should get more links with those keywords to increase your rank in that area or whether you can leave them and concentrate on another areas.
We ourselves have more than one analytics system tracking this web site to ensure that our marketing and SEO techniques are working.
Web site statistics also prove that our SEO services work and you are profiting from the work that has been done.
It is also important to be able to check the statistics of web pages that you change so that if they decrease in visitors you can then make some more changes to continually improve your visitor counts.
If your web site is selling something, don't you want to find out how many people make it from the index page to a purchase page? Of course, you want to know so you can change your web page to suit more visitors to ensure you receive more customers. We know, we try these type of tweaks on our own web sites.
Depending on where your web site is being hosted you may already have visitor tracking in place like AWStats or Webalizer. I recommend using Google’s free Google Analytics which is part of Google’s Webmaster Tools. An example of Google Analytics is shown in the thumbnail on the right. Google Analytics is the easiest to setup and use, it only requires you to setup a Google account and place a line of code on each page of your web site.
If you have your own Linux server or your web site is hosted on a Linux server you should check to see if you have server software like AWStats installed which will give you accurate and useful web site statistics.
With an endless amount of useful graph options that Google Analytics has, this would have to be the choice of web site statistics for everyone. Not only is Google Analytics used greatly for web site statistics but it is also used for helping you to earn more money or more visitors (if you use Google Adsense or Google AdWords).