Topology and Geometry of the Third-Party Domains Ecosystem

Over the years, web content has evolved from simple text and static images hosted on a single server to a complex, interactive and multimedia-rich content hosted on different servers. As a result, a modern website during its loading time fetches content not only from its owner's domain but also from a range of third-party domains providing additional functionalities and services. Here we infer the network of the third-party domains by observing the domains' interactions within users' browsers from all over the globe. We find that this network possesses structural properties commonly found in other complex networks in nature and society, such as power-law degree distribution, strong clustering, and the small-world property. These properties imply that a hyperbolic geometry underlies the ecosystem's topology and we use statistical inference methods to find the domains' coordinates in this geometry, which abstract how popular and similar the domains are. The hyperbolic map we obtain is meaningful, revealing collaborations between controversial services and social networks that have not been previously revealed. Furthermore, the map can facilitate applications, such as the prediction of third-party domains co-hosting on the same physical machine, and merging in terms of company acquisition. Such predictions cannot be made by just observing the domains' interactions within the users' browsers.