Platforms rose up out of the exquisite chaos of the web. Their founders were inspired by the freedom it promised, but also hoped to provide spaces for the web's best and most social aspects. But as these platforms grew, the chaos found its way back onto them-for obvious reasons: if I want to say something, be it inspiring or reprehensible, I want to say it where people are likely to hear me. Today, we by and large speak on platforms when we're online. Social media platforms put people at "zero distance" (Searls, 2016) from one another, afford them new opportunities to speak and interact, and organize them into networked publics (Varnelis, 2008; boyd, 2011)-and though the benefits of this may be obvious, even seem utopian at times, the perils are also painfully apparent. While scholars have long discussed the dynamics of free speech online, much of that thinking preceded the dramatic migration of online discourse to platforms (Balkin, 2004; Godwin, 2003; Lessig, 1999; Litman, 1999). By platforms, I mean sites and services that host public expression, store it on and serve it up from the cloud, organize access to it through search and recommendation, or install it onto mobile devices.