Traffic from Referring Sites

by Jakob Nielsen on April 15, 1997

Sidebar to Jakob Nielsen's column on increasing returns for websites.

The amount of traffic referred to a site from other sites seems to follow a Zipf distribution quite closely. The figure shows the distribution of traffic referred to from other websites during the first three months of 1997. Each dot on the figure represents a URL from which one or more users followed a link to Even though the data is not a perfect match with the Zipf curve, it does seem to be the case that the referrals are reasonably close to the Zipf curve. In other words, there are a few other sites that direct a lot of traffic to useit (either because these sites have very high traffic themselves or because they have prominent links to useit). Note that search engines (the blue dots) are strongly represented among these often-referring sites.

At the same time, there is a huge number of referring pages, each of which referred relatively little traffic. Because of their number, however, the total amount of users referred from these other sites still add up.

Double-logarithmic plot of traffic from referring pages
Distribution of traffic referred to from other websites in a 3-month period.
Blue dots are referrals from search engines; gray dots are all other referrals; red line is best-fit Zipf curve
Note use of a double-logarithmic scale .

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