1. The Center for Disease Control and Prevention (CDC) - The CDC is a national public health institute in the United States that works to protect public health and safety by providing information and resources to prevent and control the spread of diseases. The CDC conducts research, surveillance, and outbreak investigations to inform public health policies and practices. 2. The National Institutes of Health (NIH) - The NIH is the primary agency of the United States government responsible for biomedical and public health research. It is composed of 27 different institutes and centers, each focusing on specific areas of research such as cancer, heart disease, infectious diseases, and mental health. The NIH funds and conducts research to improve health outcomes and advance medical knowledge. 3. The World Health Organization (WHO) - The WHO is a specialized agency of the United Nations responsible for international public health. The organization works to ensure the highest possible level of health for all people, everywhere. The WHO coordinates global health initiatives, provides technical assistance to countries, conducts research, and sets international health standards and guidelines. 4. The Centers for Medicare and Medicaid Services (CMS) - The CMS is a federal agency within the U.S. Department of Health and Human Services that administers the nation's major health programs, including Medicare, Medicaid, and the Children's Health Insurance Program (CHIP). The CMS oversees health insurance coverage for more than 100 million Americans and works to improve the quality of care and reduce costs in the healthcare system. 5. The National Institute on Aging (NIA) - The NIA is one of the 27 institutes and centers that make up the NIH and is dedicated to supporting and conducting research on aging and the health and well-being of older adults. The NIA funds research on a wide range of topics related to aging, including Alzheimer's disease, caregiving, end-of-life care, and age-related diseases.