The Soil and Water Assessment Tool (SWAT) is a comprehensive, semi-distributed watershed model developed to predict the impact of land use, land management practices, and climate change on water, sediment, and agricultural chemical yields in complex watersheds. This study provides an overview of the SWAT model's structure, input data requirements, and application areas. Special attention is given to the model’s hydrological components, calibration and validation processes, and its use in sustainable water resource management. The effectiveness of SWAT in simulating long-term impacts of different scenarios on watershed health makes it a valuable tool for researchers, planners, and environmental policymakers.