Search engines may play an important role in how internet users form political opinions. Research has focused on the study of search results - but other aspects of online information related to online search have received so far less attention. The ESuPol project specifically investigated bias in search engine query suggestions, i.e., the information that appears when typing into a search bar, and potential consequences for political opinion formation. An interdisciplinary team of computer scientists, information scientists, and political scientists collected novel data of politics-related query suggestions from different search engines, such as those for national and European political actors, and query suggestions related to international events like Brexit and European elections. Leveraging large-scale data, the project investigated the existence of potential biases and how bias can be effectively and efficiently measured in search query suggestions. Moreover, the project examined the causal effects of different types of biased search query suggestions on political attitudes by using experimental methods. The project provides insights into key findings on the measurement, existence, and influence of bias in search engines on political information.