Why do we keep making decisions that go against our own best interests? In Predictably Irrational, behavioral economist Dan Ariely reveals that our choices are far from rational—and that they follow predictable patterns. In this article, we explore five key lessons from the book that explain how behavioral economics shapes our everyday decisions, from pricing and “free” offers to ownership bias and social norms. A must-read for anyone who wants to understand how and why we really decide.