Disease surveillance is the continuous, systematic collection, analysis, and interpretation of health-related data. It helps public health officials monitor the spread of diseases, identify outbreaks, and assess the effectiveness of interventions. By tracking patterns and trends, surveillance systems can provide early warnings about potential health threats, enabling timely responses to protect communities. There are various methods of disease surveillance, including active surveillance, where health officials actively seek out cases, and passive surveillance, which relies on healthcare providers to report cases. Surveillance can focus on specific diseases, such as influenza or COVID-19, and is essential for guiding public health policies and resource allocation.