Nathaniel Persily is the James B. McClatchy Professor of Law at Stanford Law School and the Co-Director of the Stanford Cyber Policy Center and Stanford Project on Democracy and the Internet. His scholarship focuses on the law and technology of democracy. Joshua A. Tucker is Professor of Politics, affiliated Professor of Russian and Slavic Studies, and affiliated Professor of Data Science at New York University. He is the Director of NYU's Jordan Center for Advanced Study of Russia, a co-Director of the NYU Center for Social Media and Politics, and a co-author/editor of the award-winning politics and policy blog The Monkey Cage at The Washington Post.

'Tackling some of the most pressing issues facing the public on the effect of social media on democracy, Persily and Tucker and contributing authors provide a grand tour of what academic research has taught us about digital politics and policy. From hate speech to polarization to misinformation and beyond, this work elucidates what we know about the impact of the Internet on democracy and presses us to think critically about how we can move this body of work forward to best inform policymaking. Social Media and Democracy should be required reading - for policymakers, academics, researchers, students of digital politics, and the general public.' Margaret Roberts, University of California, San Diego

• 1. Introduction Nathaniel Persily and Joshua A. Tucker; 2. Misinformation, Disinformation, and Online Propaganda Andrew M. Guess and Benjamin A. Lyons; 3. Social Media, Echo Chambers, and Political Polarization Pablo Barbera; 4. Online Hate Speech Alexandra A. Siegel; 5. Bots and Computational Propaganda: Automation for Communication and Control Samuel C. Woolley; 6. Online Political Advertising in the United States Erika Franklin Fowler, Michael M. Franz, and Travis N. Ridout; 7. Democratic Creative Destruction? The Effect of a Changing Media Landscape on Democracy Rasmus Kleis Nielsen and Richard Fletcher; 8. Misinformation and Its Correction Chloe Wittenberg and Adam J. Berinsky; 9. Comparative Media Regulation in the US and Europe Francis Fukuyama and Andrew Grotto; 10. Facts and Where to Find Them: Empirical Research on Internet Platforms and Online Speech Daphne Keller and Paddy Leerssen; 11. Dealing with Disinformation: Evaluating the Case for CDA 230 Amendment Tim Hwang; 12. Democratic Transparency in the Platform Society Robert Gorwa and Timothy Garton Ash; 13. Conclusion: The Challenges and Opportunities for Social Media Research Nathaniel Persily and Joshua A. Tucker.