A special issue of Information (ISSN 2078-2489), a gold open access journal published by MDPI. Deadline for manuscript submissions: 31 October 2020. *Note however that submissions received before this date will be reviewed on a rolling basis, and will be published if/when they are accepted.* For details please see: https://www.mdpi.com/journal/information/special_issues/tackling_misinformation_online -- In the last decade, social media has become the platform par excellence for all kinds of online information exchange, such as, content creation, consumption, and sharing; commenting on and engaging with content posted by others; organization of events; reporting and tracking of real world events; rating and reviewing products; and catching up with the latest developments in the news. Among the best-known platforms today are Facebook, Twitter, Sina Weibo, Reddit, and Instagram. Besides individuals, the presence of companies, agencies, institutions, and politicians has also increased on social media. One of their objectives is to engage with a broader audience, while also learning from them. For instance, companies are interested in finding out what customers think about their products in order to improve their services and perform targeted advertising. Given the scale of social media use, it is also being leveraged to perform predictions on a variety of issues, such as political elections, referenda, and stock markets. Although social media seems to offer a way to address all kinds of problems, it is also a source of new problems, some of which are a serious threat to society. One of the threats is the online information disorder and its manipulative power on public opinion. Information disorder has been categorized into the following three types: (1) misinformation, an honest mistake in information sharing; (2) disinformation, deliberate spreading of inaccurate information; and (3) malinformation, accurate information that is intended to harm others, such as leaks and cyberhate. Its spread can play an important role in shaping public opinion and reactions to events, which the viral properties of social media may then amplify. The influence of online information disorder has been evident in recent political events, such as Brexit and in Trump’s election, where social media played a significant role in shaping public opinion, and “fake news” and “post-truth” had an impact that is yet to be understood. Topics of interest include, but are not limited to, the following: * Detection and tracking of rumors * Rumor veracity classification * Fact-checking social media * Detection and analysis of disinformation, hoaxes and fake news * Stance detection in social media * Qualitative user studies assessing the use of social media * Bots detection in social media * Measuring public opinion through social media * Assessing the impact of social media on public opinion * Political analyses of social media * Real-time social media mining * NLP for social media analysis * Multimedia content analysis in social media settings * Deepfake detection and case studies * Network analysis and diffusion of dis/misinformation * Usefulness and trust analysis of social media tools * Benchmarking disinformation detection systems * Open disinformation knowledge bases and datasets --------------------------------------------------------------- For news of CHI books, courses & software, join CHI-RESOURCES mailto: [log in to unmask] To unsubscribe from CHI-ANNOUNCEMENTS send an email to mailto:[log in to unmask] For further details of CHI lists see http://listserv.acm.org ---------------------------------------------------------------