Health surveillance is the ongoing systematic collection, analysis, and interpretation of health-related data in order to monitor and track trends, patterns, and changes in health status within a population. This can include monitoring of infectious diseases, chronic conditions, environmental health hazards, occupational health risks, and other health-related factors. The goal of health surveillance is to identify potential health threats, inform public health interventions, and evaluate the effectiveness of health policies and programs. Health surveillance plays a crucial role in disease prevention, outbreak response, and overall public health management.