Public health originated in the 19th century to address poor sanitary conditions and disease outbreaks. Simple public health measures like clean water and vaccination have saved more lives than medical advances. Community medicine focuses on preventing disease in populations through organized community efforts. It aims to promote health and adjust individuals and society. Public health is defined as organized efforts to prevent disease, prolong life, and promote health through surveillance, policies, education, and ensuring resources are allocated to public health. It uses technology and social sciences to identify, prevent and monitor health issues in populations.