To gain a better understanding of user knowledge and perspectives of search engines, a fruitful approach are representative online surveys. In 2020, we conducted an online survey with a sample representative of the German online population aged 16 through 69 (N = 2,012). The online survey included 12 search engine-related sections. The questions cover topics such as usage behavior, self-assessed search engine literacy, trust in search engines, knowledge of ads and search engine optimization (SEO), ability to distinguish ads from organic results, assessments and opinions regarding SEO, and personalization of search results. SEO is the specific focus of the survey, as it was conducted as part of the SEO Effect project, dealing with issues such as the role of SEO from the user perspective. This data set contains complete data from the online survey. On the one hand, the data set will allow further analyses, and, on the other hand, comparisons with follow-up studies.