We stand in silence in check-out lines at the grocery store, distracted by our phones, barely acknowledging one another, even as rates of loneliness skyrocket. Online, we retreat into ideological silos reinforced by algorithms designed to serve us only familiar ideas and like-minded users. But what if strangers—so often blamed for our political, social, and personal problems—are actually the solution? Exploring a wide range of research, Joe Keohane reveals that even passing interactions can enhance empathy, happiness, and cognitive development, while deepening our sense of belonging.