The universe of social media is almost incomprehensibly massive: people write 500 million tweets, send 65 billion WhatsApp messages, and post four petabytes of material on Facebook every day. Lurking within this churn of content is what Howard dubs a “lie machine”: a global enterprise of bots, conspiracy theorists, politicians, scammers, authoritarian governments, and more that is devoted to spreading disinformation in the service of ideology, profit, and power. Automated, scalable, anonymous, and capable of microtargeting to the level of the individual, the machine shapes today’s politics. Its operations undermine democracies by stoking skepticism, polarizing societies, and destroying trust in all the once authoritative sources of information (including journalists, scientists, experts, and political leaders). Howard traces the evolution of the lie machine from Russia’s deployment of armies of online trolls to the use of advanced chatbots, which mimic human interaction. As dangerous as things are now, they will only get worse; the enormous flood of data coming from the so-called Internet of Things, along with the growing sophistication of artificial intelligence, will make disinformation easier to generate and disseminate and much harder to spot and remove. Howard tackles the tough task of suggesting the changes that are needed to create a radically redesigned social media ecosystem that would reinforce, rather than erode, democracy.