Concerns are increasingly being raised in journalism, politics and science about the power of big tech companies and their growing influence on society. The public, political and scientific debate often focuses on the influence of social media platforms on the functioning of democracies, such as elections and other democratic processes. There are also concerns about the influence of big tech in public domains, such as education and healthcare. The financial sector also warns about the influence of big tech companies. This background study is the first part of the triptych “From digital dependence to digital autonomy” and offers explanations for the influential and unique position of big tech companies in our society. The study is part of the Digital Dependence project, in which the Rathenau Instituut is researching the dependence of governments and public domains on the services of big tech companies.