1) The document discusses surveillance in public health and describes its key components and purposes. Surveillance involves the systematic collection, analysis, and interpretation of health data to provide information for action. 2) An effective surveillance system is simple, flexible, timely, and produces high-quality data. It addresses an important public health problem and accomplishes its objectives of understanding disease trends, detecting outbreaks, and evaluating control measures. 3) The document outlines how to establish a surveillance system, including selecting priority diseases, defining standard case definitions, and developing regular reporting and data dissemination processes. Both passive and active surveillance methods are described.