In the last decade, as the critique of mass incarceration has grown more powerful, many reformers have embraced changes that release people from prisons and jails. As educator, author, and activist James Kilgore brilliantly shows, these rapidly spreading reforms largely fall under the heading of “e-carceration”—a range of punitive technological interventions, from ankle monitors to facial recognition apps, that deprive people of their liberty, all in the name of ending mass incarceration. E-carceration can block people’s access to employment, housing, healthcare, and even the chance to spend time with loved ones. Many of these technologies gather data that lands in corporate and government databases and may lead to further punishment or the marketing of their data to Big Tech. This riveting primer on the world of techno-punishment comes from the author of award–winning Understanding Mass Incarceration. Himself a survivor of prison and e-carceration, Kilgore captures the breadth and complexity of these technologies and offers inspiring ideas on how to resist.