That is an excellent question. If your site is designed to provide a product or a service, you are obviously interested in driving as much traffic as possible to your site. An analysis of your search query terms can help you to achieve this goal.
For example, in the month of May, I had 281 requests from search engines with following phrase "redirection limit for this url exceeded." The phrase relates to a blog post I made about a problem with Firefox. Obviously, this issue was important to a lot of people. If I wrote more about it, the chances are that I would get an increase in traffic.
In fact, by looking at the top 20 or so results, I can see that people are more likely to visit my site if I write about technical issues relating to the web, than if I blog about personal issues. If I was interested in increasing traffic, I would probably write more technical articles, etc.
In short, you can use the information presented to you to optimize your site to increase traffic. You can also learn much about how search engines establish your ranking.
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