CONCLUSION Social media platforms are among the most used applications on the Internet. In the US, 85 percent of the adult population uses the Internet regularly, and 80 percent of those people are on Facebook (Greenwood, Perrin, & Duggan, 2016). Most of the time, social media are not used for politics: they are a place where friends and families connect and reconnect, or where individuals find and share entertainment, popular culture, as well as humorous cat videos. The ubiquity and prominence of social media for everyday life underscores their importance in today’s society, and users place high amounts of trust in these platforms. But with their ability to segment audiences and target messages in a quick, cheap and largely unregulated way, it is clear why these platforms have attracted the interest of political operators. Unfortunately, there is mounting evidence that social media are being used to manipulate and deceive the voting public—and to undermine democracies and degrade public life. We once celebrated the fact that social media let us express ourselves, share content, and personalize our media consumption. It is certainly difficult to tell the story of the Arab Spring without acknowledging that social media platforms allowed democracy advocates to coordinate themselves in surprising new ways: to send their demands for political change cascading across North Africa and the Middle East (Howard & Hussain, 2013). But the absence of human editors in our news feeds also makes it easy for political actors to manipulate social networks. In previous research conducted by the Computational Propaganda Project, we found rather paradoxical evidence of the chilling effect of social media on freedom of speech and political participation. Half of Russian Twitter conversations involve highly automated accounts that actively shape online discourses (Sanovich, 2017). In Brazil, both professional trolls and bots have been used aggressively to drown out minority and dissenting opinions during two Presidential campaigns, one Presidential impeachment campaign, and the major race for the Mayor of Rio (Arnaudo, 2017). Social media have gone from being the natural infrastructure for sharing collective grievances and coordinating civic engagement, to being a computational tool for social control, manipulated by canny political consultants, and available to politicians in democracies and dictatorships alike (Howard and Woolley, 2016). However, understanding precisely how social media platforms impact public life is difficult (Bradshaw & Howard, 2017). In many democracies it is not even clear that spreading computational propaganda contravenes election laws (Howard, Woolley, & Calo, 2018). It is, however, quite clear that the strategies and techniques used by government cyber troops have an impact, and that their activities violate the norms of democratic practice. We cannot prevent all bad actors from using computational propaganda, but in democracies we can have guidelines 21