The document discusses the key concepts and principles of primary health care (PHC) according to the World Health Organization (WHO) and the Philippine health care system. It defines PHC as essential health care that is universally accessible to communities at low cost through their participation. The core components of PHC include disease prevention, health promotion, and the treatment of common illnesses. It also outlines the different levels and providers of the Philippine health care delivery system from barangay health stations up to national medical centers.