The purpose of this edition of the United Nations World Water Development Report (WWDR 2022) is to shine a spotlight on groundwater, calling attention to its specific roles, challenges and opportunities in the context of water resources development, management and governance across the world. Groundwater accounting for approximately 99% of all liquid freshwater on Earth and distributed over the entire globe, albeit unequally has the potential to provide societies with tremendous social, economic and environmental benefits, including climate change adaptation. Groundwater already provides half of the volume of water withdrawn for domestic use by the global population, and around 25% of all water withdrawn for irrigation, serving 38% of the worlds irrigated land. Yet, despite its enormous importance, this natural resource is often poorly understood, and consequently undervalued, mismanaged and even abused. In the context of growing water scarcity in many parts of the world, the vast potential of groundwater and the need to manage it carefully can no longer be overlooked.