"This Synthesis Report provides a formal systematic review of scientific literature on countermeasures for mitigating digital misinformation. 588 peer-reviewed global publications from many disciplines were the focus of this study in order to highlight the most effective countermeasures for mitigating potential effects of misinformation, disinformation, and a range of related phenomena. According to the report’s selected publications, the four most often endorsed countermeasures are corrective information materials, information and media literacy content, content moderation, and content labeling. More than 10% of the analyzed publications validated these countermeasures. Research reveals several patterns in the investigation of countermeasures for combating misinformation across disciplines. Social sciences emerge as a leading area of scholarship in exploring various strategies, with one exception: content moderation, which is more actively tested in publications from the physical sciences. Simultaneously, experiment-based methodologies highlight content labeling and content reporting as the most effective countermeasures. There is no substantial geographic variation in what researchers are finding. Five important limitations in current research were identified: 1. Few publications test specific countermeasures with real-world data; 2. Some of the solutions offered in the literature are too broad to be tested; 3. Methods that are more likely to bring critical perspectives, such as interviews, focus groups, and discourse analysis, are used less often than quantitative methods; 4. Some countermeasures are understudied in particular disciplines. For example, redirection, or information and media literacy are understudied in the health and physical sciences; 5. The literature in English that is analyzed pays insufficient attention to the problem beyond a few Western countries." (Synopsis)