For decades, GIS has been taught from a bottom-up perspective in which basic concepts, tools, and tasks are first introduced in great detail, then linked together to form higher level parts of the system. These are in turn linked, sometimes across many levels, until the complete top-level geographic information system is revealed. This approach often results in a view of GIS as muddle of tools, functions, properties, and subsystems, seemingly isolated, task-specific, and fragmented. LearnGIS replaces this piecewise approach with a top-down, integrated view of GIS as a platform, based on the science of geography, that provides open geospatial capabilities to any user and allows access by any application on any device. In our top-down approach, we demonstrate through real-world examples how GIS solves geographic problems and builds geospatial knowledge. The examples, illustrating how GIS is used to conceptualize, organize, analyze, and visualize geographic information, introduce relevant GIS concepts, functions, and uses in yet greater detail. The exercises come to life when readers apply the methods in an interactive, engaging, and fun social learning environment. With the ArcGIS platform, all the maps, data, and tools are online, so anyone can learn by doing at anytime, anywhere, as long as they have Internet access. Through interactive story-telling and hands-on applications, we build a progressive understanding of the entire GIS platform, as a collection of its base elements (online maps, apps, tools, workflows, …), assembled in an integrated fashion, and used to find the solutions and information desired.