Karolina Koc-Michalska is Professor at Audencia Business School and Affiliated Researcher at CEVIPOF Sciences Po Paris, France, and University of Silesia, Poland. She is part of the NEPOCS group ([...]). She studies the strategies of political actors in the online environment and citizens' political engagement. She employs a comparative approach focusing on the United States and European countries.

Ulrike Klinger is Professor for Digital Democracy at the European New School of Digital Studies, European University Viadrina, Frankfurt (Oder) in Germany. Her research focuses on digital political communication, technology and democracy, and the transformation of public spheres.

Lance Bennett is Senior Research Fellow, Center for Journalism, Media & Democracy at the University of Washington, Seattle.

Andrea Römmele is Dean of Executive Education and Professor of Communication in Politics and Civil Society at the Hertie School. Her research interests are comparative political communications, political parties and public affairs.

Introduction - Dissonant Public Spheres: Communication, Campaigns and Crises 1. Conditions of Campaigning in Dissonant Public Spheres and Crisis of Democracy 2. Data-Driven Campaigning as a Disruptive Force 3. The Data Abyss: How lack of data access leaves research and society in the dark 4. Farewell to Big Data? Studying Misinformation in Mobile Messaging Applications 5. Cross-Platform Emotions and Audience Engagement in Social Media Political Campaigning: Comparing Candidates' Facebook and Instagram Images in the 2020 US Election 6. Are Campaigns Getting Uglier, and Who Is to Blame? Negativity, Dramatization and Populism on Facebook in the 2014 and 2019 EP Election Campaigns 7. Damage Control: How Campaign Teams Interpret and Respond to Online Incivility 8. Dissonance from the Perspective of Agonistic Pluralism: A Study of Political Fragmentation on Facebook during the 2016 Austrian Presidential Election 9. The Campaign Disinformation Divide: Believing and Sharing News in the 2019 UK General Election 10. Abating Dissonant Public Spheres: Exploring the Effects of Affective, Ideological and Perceived Societal Political Polarization on Social Media Political Persuasion 11. Broadcasting Messages via Telegram: Pro-Government Social Media Control During the 2020 Protests in Belarus and 2022 Anti-War Protests in Russia 12. Political Polarization on the Digital Sphere: A Cross-platform, Over-time Analysis of Interactional, Positional, and Affective Polarization on Social Media