Springs have been the focus of attention throughout human evolutionary history, and are nearly universally recognized as highly productive, bio-culturally essential, and economically important ecosystems. While of recognized value and arguably among the most sustainable ecosystems, these ecosystems also have been reported as being ecologically compromised by intensive anthropogenic management. However, the global conservation status of spring ecosystems has not previously been evaluated. To address data gaps, misinformation, and the many uncertainties about the sustainability of aquifer and springs, Cantonati et al. (2020) called for improving public and governmental awareness of spring ecosystems, as well as additional basic mapping, inventory, and assessment to determine the distribution and ecological integrity of springs globally. The impetus for the present work is, in part, in response to their concerns. In this book we present synopses on the distribution, typology, ecology, anthropogenic uses, and conservation status of >250,000 springs from all continents except Antarctica, from a total of 75 countries and in some cases from multiple states or geologic provinces within countries. This information was derived from our individual studies and from the literature, and serves as the foundation of the first analysis on the ecological status of the world’s spring ecosystems, as summarized by Stevens et al. (2021). Collectively, we report that the ecological integrity of springs is gravely threatened in most regions, particularly in arid and semi-arid regions where water supplies are most limited. The intensity of human impacts on springs and the species and assemblages supported by springs is less clearly identified in the tropics and other humid regions, but generally increases from low to middle latitudes. Human impacts on groundwater availability and quality, local geomorphology, and habitat quality increase with proximity to urban, industrial, and mining development, particularly in regions subject to intensive agriculture. We find that the assumption that springs are only of management concern in arid regions is erroneous: springs everywhere around the world serve many important cultural and socio-economic functions and suffer from generally similar kinds of human impacts. This effort is, of necessity, a preliminary presentation, because many information and management policy gaps exist, even in countries that recognize the biologically and socio-cultural significance of springs. Basic geographic data and consistent, statistically credible assessment approaches, as well as improved relational and comparative information management are needed everywhere to improve understanding of the distribution, types, associated attributes and species, and ecological status of springs. Existing assessment approaches, such as those proposed by the IUCN’s Red List of Ecosystems are laudable, but are complicated by the insular, island-like, and highly individualistic nature of spring ecosystems. Despite many information gaps, our study concludes that springs are globally threatened, and that efforts to maintain springs sustainability must extend to the supporting aquifer, as well as the landscapes into which the springs emerge. Assessment of spring ecosystems should involve random selection of a suitably large number of springs within the study area or nation, with stratification based on the salient variables distinguishing springs types, including geomorphic type, vegetation, and elevation. While challenging to assemble, such data and relational information management are needed to ensure appropriate assessment, prioritization, planning, implementation, and monitoring of stewardship. Our insights into spring ecosystem distribution, ecology, and conservation status reveal that these often critically important ecosystems and their associated species and attributes are highly imperiled globally and warrant significant public, scientific, and managerial attention.