Primary health care (PHC) aims to provide comprehensive, affordable care that is as close to communities as possible. The key principles of PHC are that it is socially appropriate, universally accessible, and focuses on those most in need. PHC addresses major health problems through promotion, prevention, treatment, and rehabilitation services. It incorporates related sectors like agriculture, education, and housing. PHC relies on community participation and self-reliance. Its core activities include education on health problems, nutrition, immunization, and treatment of common illnesses. PHC forms the basis of broader health systems by organizing resources to promote health and narrow health inequalities.