Hospital length of stay is a core metric and significant performance indicator within healthcare research and health systems analysis. It represents the duration a patient remains admitted to a hospital facility for inpatient care. As a research concept, it investigates the factors influencing the length of inpatient stays (determinants), its relationship with healthcare resource utilization, costs, quality of care, and patient outcomes. Measured typically from admission to discharge, often aggregated into metrics like Average Length of Stay (ALOS), its significance lies in its utility as a proxy for hospital efficiency, resource management, and service delivery effectiveness, highlighting variations in clinical practice and patient complexity.