The main topic of public health is to promote and protect the health of populations through organized efforts and informed choices. Public health encompasses prevention of disease, prolonging life, and promoting health through activities like health education, policy-making, and community interventions. It looks at various factors that influence health, such as environmental, social, and economic conditions. Public health professionals often focus on issues like vaccination, disease control, health equity, and access to healthcare services, aiming to improve overall health outcomes and reduce health disparities in different populations.