  Coordination is a fundamental aspect of life. The advent of social media has
made it integral also to online human interactions, such as those that
characterize thriving online communities and social movements. At the same
time, coordination is also core to effective disinformation, manipulation, and
hate campaigns. This survey collects, categorizes, and critically discusses the
body of work produced as a result of the growing interest on coordinated online
behavior. We reconcile industry and academic definitions, propose a
comprehensive framework to study coordinated online behavior, and review and
critically discuss the existing detection and characterization methods. Our
analysis identifies open challenges and promising directions of research,
serving as a guide for scholars, practitioners, and policymakers in
understanding and addressing the complexities inherent to online coordination.
