Knowing how visitors found you is as or more important than knowing what they do on your web site. Referring URLs are (usually) the source of this type of information.
Nearly all web measurement programs provide a basic top-level referring domains report as well as an option to drill down into the details of each referring URL. Data overload is a common problem when you're thinking about your referrers, and often it's best to simplify your referrers to show only the domain. However, in some cases you'll be forced to analyze the entire referring URL (Figure 3-15).
Figure 3-15. Referring URLs report
Since the referrer exists only when a link is constructed from another site to yours, the referrer is one of the most exciting things ...