Population health surveillance is a public health activity whose purpose is to continuously collect information on health events and to analyze this information in order to construct numerical indicators and map them, as well as to disseminate the results in order to provide assistance to decision-makers in the field of human and animal health. Mainly developed since the 1950s, over the decades, it has become an essential tool for the development and implementation of all health policies, following the success of health crises. According to the definition developed in the 1950s by the U.S. Centers for Disease Control and Prevention (CDC), " Epidemiological surveillance is a systematic process of collection, interpretation, and analysis of data on specific health events important to the design, execution, and assessment of public health practices, tightly coupled with their accurate dissemination to those who need to know." This is not dissimilar to the definition used by the World Health Organization, which is reflected in many of its documents, such as the International Health Regulations: "Surveillance is the systematic and continuous collection, collation and analysis of data for public health purposes and the timely dissemination of public health information for public health assessment and action, where appropriate". No standardized definition exists, but these correspond to some international consensus. In addition to the definition, it is accepted in France that epidemiological surveillance must be regularly evaluated. In the USA, the preferred name is Public Health Surveillance. The principal objectives of epidemiological surveillance systems are to describe, alert and evaluate. Describe the dynamics of a health phenomenon (disease, syndrome, symptom, behavior, etc.) in a population with known boundaries (city, region, and country) over time. To warn, or give the alert, by detecting as early as possible in the monitored population any unexpected, anomalous, or epidemic phenomenon. To assess, for a given period and in the population monitored, the impact of public health programs and policies (prevention, education, screening, treatment programs, and so on).