<p>Water scarcity is increasingly shaped by the interaction of physical limits, economic constraints, water-quality deterioration, and governance failure. This review synthesizes recent evidence on global water scarcity by examining climatic, anthropogenic, environmental, socio-economic, and political drivers; comparing regional manifestations; and evaluating mitigation options across technological, institutional, and nature-based domains. The review clarifies that scarcity should not be assessed only through per-capita volumetric indicators, because crisis conditions emerge when low availability coincides with poor access, unreliable infrastructure, degraded quality, weak institutions, and limited adaptive capacity. Agriculture remains the dominant freshwater-consuming sector, and therefore water-footprint management, crop planning, irrigation efficiency, deficit irrigation, drought-resistant crops, and allocation rules are central to any credible scarcity-reduction strategy. The analysis also compares interventions such as wastewater reuse, desalination, rainwater harvesting, managed aquifer recharge, efficient irrigation, economic instruments, groundwater monitoring, transboundary cooperation, and nature-based solutions in terms of feasibility, trade-offs, costs, and implementation risks. The review concludes that sustainable water security requires a differentiated response: physical scarcity demands demand management, reuse, allocation reform, and non-conventional supplies, whereas economic scarcity requires infrastructure investment, transparent governance, institutional capacity, and inclusive public participation.</p>