The overall goal of the project is to describe and explain the role of search engine optimization from the perspective of the participating stakeholder groups by analysing search results/search result pages for optimized content as well as quantitative and qualitative surveys of search engine users, search engine optimizers and content providers. Thus the external influence on the results of commercial search engines can be described and quantified for the first time. The project contributes to theory building in information science by extending existing information-seeking models by a component of external influence on the search results.The project focuses on informative content; it examines how documents that play a role in answering information-oriented search queries can be influenced externally. This sets the project apart from pure questions of online marketing, where the focus is on the optimization itself and not on the consequences for the compilation of result sets.To measure the effect of search engine optimization, a software will be developed that can automatically query search engines and analyze the returned results. The results of the search result analyses carried out using it are combined with findings from the survey and further investigations of search engine users, search engine optimisers and content providers in order to obtain a comprehensive picture of the influence of search engine optimisation. Methodologically, the project is characterized by a triangulation of methods of data analysis from computer science and social science methods. The interdisciplinary basis of the analysis is unique and will significantly advance the understanding of search engines in general and the influence search engine optimization has in particular.With search engine optimization, the project addresses a highly relevant topic for information seeking in society, which to a considerable extent takes place via commercial search engines. The expected empirical and theoretical results contribute to a better understanding of information seeking in the context of modern web infrastructures. At the level of transfer into practice, the results will be relevant to issues like consumer protection.