The 20th century witnessed two digital revolutions. Computing power has revolutionized every industry, from finance to agriculture to pharmaceuticals. We've got computers at work and at home, in our pockets and our bags, on our wrists, and even embedded in the architecture of our houses. At the same time a revolution in digital communication unfolded, which has forever altered our lives-work, social, and private-by enabling a world in which we're never impossible to reach and have nearly limitless power to express ourselves. But no one saw the downsides of these: powerful computers threaten to displace human labor from a range of jobs, both blue and white collar, and, after an election in which the Internet played such a pivotal role in spreading disinformation-not to mention the simple problem of never being able to escape our jobs if our email goes with us everywhere-the possible pitfalls of free communication become clearer.And now, as Alan Gershenfeld, Joel Cutcher-Gershenfeld, and Alan Gershenfeld make clear, we are in the early years of the third digital revolution: from computation and communication comes fabrication. Fabrication includes everything from 3D printing to laser cutters to machines that can assemble anything, including themselves, by precisely controlling the placement of individual atoms. We will soon be able to program matter the same way we can now program a computer. This may sound outlandish, but just as the smartphone is the logical conclusion of trends in computing that began in the 1960s, so is this fabrication technology of the future the extension of today's trends in manufacturing. Neil Gershenfeld, an MIT professor, is at the forefront of making it a reality, through his scientific work as well as his championing of Fab Labs, a sort of low-cost personal factory. In Designing Reality, he and his brothers Alan and Joel explore not just the promise but the perils of this revolution in fabrication. On one extreme, it promises self-sufficient cities, the end of work, and the ability for each of us to design and create anything we can imagine. On the other, it could lead to the concentration of wealth in very few hands. Neither guaranteeing utopia nor insisting that our worst nightmares are about to come true, the Gershenfelds are trying to anticipate the future and teach us how best to prepare for it, personally and as a society, across education, employment and more. The first two digital revolutions caught us flat-footed, and there has been a heavy price to pay. Let us prepare for the future, not simply react to it.