Journal of Web Science, 2018, 4: 53–66 On the Ubiquity of Web Tracking: Insights from a Billion-Page Web Crawl Sebastian Schelter1 and Jérôme Kunegis2 1Database Systems and Information Management Group, Technische Universität Berlin, Germany
[email protected] 2Namur Center for Complex Systems, University of Namur, Belgium
[email protected] ABSTRACT We perform a large-scale analysis of third-party trackers on the World Wide Web. We extract third-party embed- dings from more than 3.5 billion web pages of the CommonCrawl 2012 corpus, and aggregate those to a dataset containing more than 140 million third-party embeddings in over 41 million domains. We study this data on several levels and provide the following contributions: (1) Our work leverages the largest empirical web tracking dataset collected so far, and exceeds related studies by more than an order of magnitude in the number of domains and web pages analyzed. As our dataset also contains the link structure of the web, we are able to derive a ranking measure for tracker occurrences based on aggregated network centrality rather than simple domain counts. We make our extracted data and computed rankings available to the research community. (2) On a global level, we give a precise figure for the extent of tracking, give insights into the structural properties of the ‘online tracking sphere’ and analyse which trackers (and subsequently, which companies) are used by how many websites, leveraging our ranking measure derived from the link structure of the web. (3) On a country-specific level, we analyse which trackers are used by websites in different countries, and identify the countries in which websites choose significantly different trackers than in the rest of the world.