Each site is represented by a circle, whose size depends on the amount of traffic, and the space between each one is determined by the frequency with which users jump from one to another.
As one might have expected, the largest clusters are formed by national websites, i.e. sites belonging to one country. For the sake of convenience, all websites relative to a certain country carry the same color. For instance, the red zone at the top corresponds to Russian segment of the net, the yellow one on the left stands for the Chinese segment, the purple one on the right is Japanese, the large light-blue central one is the American segment, etc.