Internet marketing efforts need to be tracked so you know if you are using your resources wisely. Google analytics is a good, free tool you can use to track traffic sources, conversion rates, etc.
Make sure you have Google analytics or some other type of analytics installed on your website.
You want to know where your traffic is coming from and where it is not coming from. This will help you allocate your resources properly. Google Analytics is able to track where your site visitors are coming from, where they go on your site, etc.
A few examples of where your traffic may come from:
Search Engines (Google, Yahoo, Bing, etc)
Twitter, Facebook, etc
Articles and press releases that include links
Websites that have your links
Having this information can help you have a more effective Internet marketing plan.
Easy Come, Easy Go
It is easy to find out where the traffic comes from and what page they leave from. Both of these pieces of information are valuable. Knowing them can help you identify if your Internet marketing strategy is working.
The page people enter your site on is important. You want to make sure they arrive on your website on a page that has a focused message for what they are looking for (most websites have multiple entry points, each focused on a different search term). Pay careful attention to what page your visitors land on and make sure it is well designed and well written.
The page visitors leave your website on is also important because it may identify a problem with your site. If you find that a certain page is the primary exit point you want to see if there are any technical or other issues with that page that make people leave your site.