We live in the age of the algorithm. Increasingly the decisions that affect our lives - where we go to school, whether we get a car loan, how much we pay for health insurance - are being made not by humans but by mathematical models. In theory this should lead to greater fairness. But as Cathy O'Neil reveals in this urgent and necessary book, the opposite is true. Tracing the arc of a person's life, O'Neil exposes the black-box models that shape our future, both as individuals and as a society.