Public health systems are organized efforts by governments and communities to protect and improve the health of populations. They focus on preventing diseases, promoting healthy lifestyles, and ensuring access to medical care. Key components include vaccination programs, health education, and disease surveillance, which help identify and respond to health threats. These systems work through various agencies, such as the World Health Organization (WHO) and local health departments, to coordinate responses to health issues. By addressing factors like nutrition, sanitation, and environmental health, public health systems aim to create healthier communities and reduce health disparities among different populations.