When TheFacebook.com went live in February of 2004, social media quickly became an integral part of life. Old friends rediscovered each other, pet photography flourished, and the way human attention on the internet was distributed was altered forever. As Ben Smith describes in his recent book, Traffic, before Facebook (now Meta) became widely adopted, aggregators like The Huffington Post and the Drudge Report were the main drivers of traffic to websites. Now they have been supplanted by social media platforms. This has transformed the internet business, politics, and journalism. Along the way, Facebook has accumulated a treasure trove of social science data on human reading habits and engagement. In this issue, Science is publishing three research papers and a Policy Forum that arose from an innovative partnership between Meta and academic researchers and illuminate our understanding of American political behavior.