Why social media platforms have a responsibility to look after their platforms, how they can achieve the transparency needed, and what they should do when harms arise. The large, corporate global platforms networking the world's publics now host most of the world's information and communication. Much has been written about social media platforms, and many have argued for platform accountability, responsibility, and transparency. But relatively few works have tried to place platform dynamics and challenges in the context of history, especially with an eye toward sensibly regulating these communications technologies. In Governing Babel, John Wihbey articulates a point of view in the ongoing, high-stakes debate over social media platforms and free speech about how these companies ought to manage their tremendous power. Wihbey takes readers on a journey into the high-pressure and controversial world of social media content moderation, looking at issues through relevant cultural, legal, historical, and global lenses. The book addresses a vast challenge--how to create new rules to deal with the ills of our communications and media systems--but the central argument it develops is relatively simple. The idea is that those who create and manage systems for communications hosting user-generated content have both a responsibility to look after their platforms and have a duty to respond to problems. They must, in effect, adopt a central response principle that allows their platforms to take reasonable action when potential harms present themselves. And finally, they should be judged, and subject to sanction, according to the good faith and persistence of their efforts.