Why do crickets harmonize together in choruses on a summer night? What makes the moon spin precisely in sync with its orbit? Why do audiences clap simultaneously? What made the Millennium Bridge wobble? The answer in sync. The tendency to synchronize is one of the most far-reaching drives in the universe, extending from people to plants, animals to atoms. Here Steven Strogatz, leading researcher in chaos-and-complexity theory, explores the deep connection that links these phenomena- the mathematical theory of self-organization, where millions of simultaneous interactions result in order emerging from chaos. Sync tells the story of this dazzling harmony - the cycles and patterns that fit together like clockwork to affect our lives at every level.