Although the world’s attention has shifted to drone-controlled bombing and cyberwarfare, the threat of nuclear war still exists. There are now fourteen thousand nuclear weapons in the hands of the nine declared nuclear powers. Even though the world survived the Cold War, we need to understand what it means to live with nuclear weapons. In this volume in the MIT Press Essential Knowledge series, Mark Wolverton offers a primer on nuclear weapons, from the science of fission and fusion to the pursuit of mutual assured destruction, the SALT and START agreements, and the Bomb in pop culture.